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Double Asymmetries

Thomas Andrews; © 2000-2009.

Introduction

We've all seen contracts which can make more tricks declared from one side than the other. A typical example is:
A K
K Q 10 9
A K 10 9 8
9 8
J 10 9 8
8 7 6
7 6 5
A Q 7
7 6 5 4
J 5
4 3
J 10 6 5 4
Q 3 2
A 4 3 2
Q J 2
K 3 2
If North declares 6 NT or 6 ♥, East can set it with a club lead. But when declared by South, both slam makes, scoring five diamonds, four hearts, and three spades.
The ♣ K-3-2 holding is an asymmetric guard - a holding which can only be profitable attacked from one side.
This idea led me to ask the question, "Are there deals which play better by North in, say, hearts, but better by South in notrump?"
Here is just such a deal:
Q 4
A K Q J 9 2
4
A 8 6 5
8 6
7 4 3
K 3
Q J 10 9 7 3
J 10 9 5
10 6 5
Q 9 8 6 5 2
—
A K 7 3 2
8
A J 10 7
K 4 2
In choosing between grand slams, obviously South cannot declare the heart contract - West could give his partner a ruff immediately.
On the other hand, North can easily make 7 ♥, by drawing trumps then setting up the spades with one ruff.
What about the 7 NT contract? On a non-diamond lead, 7 NT can be made. Declarer simply cashes his top black cards then runs his hearts, getting to this position:
—
2
4
6
—
—
K 3
Q
J
—
Q 9
—
7
—
A J
—
This is the standard double-squeeze position. On the last heart, East must keep his spade, and therefore must pitch a diamond. South's spade is then pitched, and West must give up in clubs or diamonds.
But what of a diamond lead? When led by East, the diamond lead does, indeed, ruin declarer's chances. When led by West, declarer's double squeeze vanished, but is replaced by a simple squeeze.
Why is that? Because the lead from the West hand requires one of East or West to commit a diamond honor to the first trick. This leaves only one defender guarding the suit.
For example, if West leads the ♦ K, South wins in hand, cashes his two top club tricks, and runs his hearts to this position:
Q 2
2
—
8 6
8 6
—
3
Q J
J 10 9 5
—
Q
—
A K 7 2
—
J
—
On this last heart, East is squeezed in spades and diamonds.
If West instead opened with a low diamond, East would have to contribute the ♦ Q, and West would be squeezed at the end in diamonds and clubs.
This first example of an Asymmetric Deal employs a cop-out - East's void is what makes the 7 ♥ contract fail. Declarer's club holding can hardly be called an asymmetric guard. The rest of the examples will show more subtle types of positions. Most of these hands require careful study for each of the four (sometimes six!) possible contracts under discussion. In these deals, both declarer and the defenders often have to walk a very thin line to maximize their results.
Fundamentally, these are double-dummy problems, so I will not try to construct auctions, or explain what might lead a declarer to take one line over another. I am not so accomplished a bridge writer that I can create such fictions and not make them seem forced. It is unlikely that many of the lines described herein would be found at the table.

Finding Deals

Doubly asymmetric deals are rare, and require an eagle eye. Thankfully, I can employ a computer's eagle eye. I have employed two computer programs:
  • Deal, my own flexible dealer.
  • GIB, a double dummy solver written by Matt Ginsberg.
  • More recently, I've been using the newest version of Deal which includes a builtin double-dummy solver.
I've written an interface between Deal and GIB which allows me to find deals with interesting double-dummy properties.
Once the deals were found, I sifted through them myself, and extracted what I thought were the most interesting examples. I hope you enjoy them.

Thomas Andrews; © 2000-2009.

A First Look

J 2
A K 9 7
A Q J 4
J 9 6
6 4
10 6 5 3
K 10 9 7 5
A Q
A 9 3
Q J 4 2
8 2
8 7 5 3
K Q 10 8 7 5
8
6 3
K 10 4 2
In this example of double asymmetry, North/South might consider game in either spades or notrump.

Spades

If South declares the 4 ♠ contract, all is well - the opponents will get their three black winners and no more.
If North declares 4 ♠, though, the club lead sets it, because the defense gets two clubs, the trump ace, and a club ruff.

Notrump

South cannot make 3 NT on a heart lead from West. Twist and turn as he might, he cannot avoid losing two hearts, two clubs, and a spade before he can run his nine apparent tricks.
On the other hand, if North declares in 3 NT, he cannot be set by a heart or any other lead.
On a low heart lead, North wins West's ♥ 10 with the ace, and leads the ♠ J. East has to duck this, to keep declarer from running five spades when he gets in next. North continues with a spade and East can safely win this trick, leading to this position:
—
K 9 7
A Q J 4
J 9 6
—
6 5 3
K 10 9 7 5
A Q
9
Q J 4
8 2
8 7 5 3
K Q 10 8
—
6 3
K 10 4 2
East cannot attack hearts himself here, because that would give declarer a third stopper. So he has to lead a club to West's queen.
West continues with a heart, ducked to East, and East again cannot lead hearts, holding ♥ Q-4 and North holding ♥ K-7. West gets in one more time to lead hearts, but North still has the ♥ K, and the defense fails to collect its five tricks before declarer makes his nine.

Thomas Andrews; © 2000-2009.

A One-sided Blockage

Q J 9 5
K
J 8 4
A J 10 6 4
K 10 4 2
9 8 3 2
Q 7 6 5 3
—
6 3
7 5
A K 10 9
Q 8 5 3 2
A 8 7
A Q J 10 6 4
2
K 9 7
In this deal, 4 ♥ and 4 ♠ can only be made declared by South.
If North declares a major game, East can lead a club, ruffed, win a diamond return, and give West another ruff. Eventually, the defense gets the spade king as well.
But 3 NT can only make when declared by North.
The secret here is that if West leads diamonds, the defense can successfully unblock the diamond suit. But if East leads diamonds, the suit blocks, and the defense can only take four top tricks.

Thomas Andrews; © 2000-2009.

A Two-way Blockage

10 9 2
Q 5 2
Q 7 5 2
K J 4
4 3
A J 9 8
A J 10 8
6 3 2
8 6 5
6 4 3
K 9 3
9 8 7 5
A K Q J 7
K 10 7
6 4
A Q 10

Notrump

Only North can make 3 NT. If South declares notrump, then west can start with the ♦ J, and the defense starts with three diamonds, then a heart to the ace, and a fourth diamond.
But if East is on lead, the diamond suit is blocked. The defense can take three diamonds off the top, but then North's ♦ Q is good.

Spades

The trick here is to avoid letting East lead hearts twice. If North is declarer in spades, then East can lead hearts, and then again when he gets on lead with the ♦ K.
But if South is declarer, she can keep East from winning two diamonds by playing the ♦ Q if West leads the ♦ 8, and plays small diamonds otherwise. The suit is safely blocked. When East gets in with the diamond queen and leads a heart, south plays the ♥ K, and West must win the ace.
Declarer can easily achieve this end position:
—
Q 5
7
—
—
J 9
A
—
—
6 4
—
9
J
10 7
—
—
On the last spade, West is squeezed in the red suits.

Thomas Andrews; © 2000-2009.

Trashing Entries

Q 9 5 4
A Q J 7 3
6 3
A Q
K 8 6
9 5 4 2
A J
9 7 5 2
J 10 7 3
K 8 6
10 4
K 10 4 3
A 2
10
K Q 9 8 7 5 2
J 8 6
This is our first Double Asymmetry where immediate shortness and ruffing does not obviously contribute to some of the asymmetry.

Three Notrump, by North

North, declaring 3 NT, cannot make against best defense. East leads a low spade, and declarer ducks. West wins the king and continues spades. This puts North in a quandary - he has lost his only entry to dummy before the diamonds are set up.
Still, he has what appears to be two club tricks, two spade tricks, four heart tricks, and a diamond, if he can get them in time.
So declarer leads the ♥ 10, finessing, and East ducks.
Declarer then finesses in clubs, and East wins. At this position:
Q 9
A Q J 7
6 3
A
8
9 5 4
A J
9 7 5
J 10
K 8
10 4
10 4 3
—
—
K Q 9 8 7 5 2
J 8
East can set declarer by leading a spade; the defense eventually getting a total of two spades, a club, a heart, and a diamond.

Three Notrump, by South

The spade lead from East served two functions - first, it killed South's entry to the long diamonds, and second, it did so without providing declarer a second entry to North's hand.
If South declares, on the other hand, West can kill the diamond suit by leading the ♠ K, but this give South two things in return. The first is the immediate tempo advantage of having his second spade trick set up right away. The second is that the spade suit provides an interesting threat to East at the end position.
After the ♠ K lead, South wins the ♠ A, and the play proceeds much as above. Declarer leads the ♥ 10, ducked all around. Declarer then takes the club finesse. East wins at this position:
Q 9 5
A Q J 7
6 3
A
8 6
9 5 4
A J
9 7 5
J 10 7
K 8
10 4
10 4 3
2
—
K Q 9 8 7 5 2
J 8
East naturally leads the ♠ J, West unblocks the eight and declarer's queen wins. Declarer then unblocks the ♣ A, and leads a diamond to the king. West must duck the first diamond. If he wins and shifts to spades, his side gets two spades, the ♦ A and the ♣ K, but then the diamonds are good.
Declarer then strands himself completely by continuing diamonds. West wins at this position:
9 5
A Q J 7
—
—
6
9 5 4
—
9 7
10 7
K 8
—
10 4
—
—
Q 9 8 7 5
J
West obviously cannot lead a club, or South's hand is good.
If West leads a spade, East gets his two spade tricks, but then must surrender the rest of the tricks by leading a heart (setting up North) or a club (to the good South hand.)
If West leads a heart, South hops up with the ♥ A and continues hearts, and again East is thrown in, this time with the ♠ 9 a threat in dummy.
Whatever West leads, his side can only get two more tricks.
Perhaps East should not have exited a spade when in with the ♣ K? It does not matter; declarer can reach a substantially similar end-position:
Q 9 5
A Q J 7
—
—
8 6
9 5 4
—
9 7
J 10 7
K 8
—
10 4
2
—
Q 9 8 7 5
J
West again on lead with the ♦ A, and again the defense cannot take more than two tricks. This time, if West leads a heart, declarer wins the ace, exits a heart, and then must duck the first spade to finish the endplay.
So, 3 NT makes only if declared by South on the above hand.

Five Diamonds, by South

Q 9 5 4
A Q J 7 3
6 3
A Q
K 8 6
9 5 4 2
A J
9 7 5 2
J 10 7 3
K 8 6
10 4
K 10 4 3
A 2
10
K Q 9 8 7 5 2
J 8 6
Now, what about the 5 ♦ contract?
West leads a club, and the finesse is taken. East continues a club. Declarer then leads the ♥ A and ♥ Q, forcing East to cover. Declarer ruffs low, and must ruff his good ♣ J in dummy to pitch his spade loser on the ♥ J. Declarer is now at this position:
Q 9 5 4
7 3
6
—
K 8 6
9
A J
9
J 10 7 3
—
10 4
10
A
—
K Q 9 8 7 5
—
Declarer cannot avoid a second diamond loser. If he leads a diamond to the king, West wins the ace and continues with the ♥ 9. East ruffs with the ♦ 10, and West's ♦ J is promoted.
The attack of the club suit killed a vital entry. Without that lead, declarer could afford to pitch the spade loser after the trumps are drawn.

Five Diamonds, by North

So maybe 5 ♦ can make if North declares? Indeed, it can. It may appear that East can lead a spade to set the contract, but that is an illusion.
North calls for the ♠ A, then plays the ♥ A and ♥ Q immediately. East must cover, and declarer ruffs. Declarer then leads the ♦ K, West winning at this position:
Q 9 5
J 7 3
6
A Q
K 8
9 5
J
9 7 5 2
J 10 7
8
10
K 10 4 3
2
—
Q 9 8 7 5
J 8 6
West is caught in something like "Morton's Fork." If he cashes the ♠ K, declarer can pitch two clubs on major-suit winners in hand. And if West does not cash the ♠ K, the spade winner vanished on the ♥ J. In either case, declarer is able to get rid of one of his black suit losers.

Post-mortem

This is a rather astounding deal.
  • 3 NT fails declared by North because a vital spade entry can be killed immediately.
  • 3 NT makes declared by South because the cost of killing the spade entry is too high, leading to a stunning endplay, with declarer deliberately destroying all of his entries.
  • 5 ♦ fails declared by South, because a natural club entry is killed, forcing South to ruff a winner to pitch a loser, which in turn forces South to delay pulling trumps until after pitching is loser, which lets East/West score a second trump on a trump promotion.
  • 5 ♦ makes declared by North, because the club entry is preserved, allowing North to lead trumps. West is caught in a Morton's Fork, having to choose which black suit loser he wants to let declarer pitch.
Okay, I warned you these would be complicated.
The two black suit holdings are providing subtle protection, even though they look like traditional guards. In both cases, the ace of the suit is providing a vital entry, and in both cases, that entry can be knocked out safely from only one side.

Thomas Andrews; © 2000-2009.

A Three-way Example

A 9 8 7 5 2
A Q
K
Q J 10 5
Q 10 4
J 7 6 5
10 7 3
K 7 2
6 3
K 10 8 2
J 5 4
9 6 4 3
K J
9 4 3
A Q 9 8 6 2
A 6
There are actually three strains possible on this hand - notrump, spades, and diamonds - and North/South can make slam from only one side in each strain.

Notrump

After a heart lead by West, 6 NT cannot make. There are 10 top tricks, and declarer will need to set up two more to make his slam, but he needs to lose the lead to West in spades or clubs to do this, at which point the defense can take a couple more heart tricks.
Declarer can run a strip squeeze against West to get an 11th trick, if 5 NT is the contract. Declarer loses the heart finesse and wins the heart return. He then cashes the ♦ K, crosses to the ♠ K and runs the diamonds:
A 9 8
—
—
Q J
Q 10
5
—
K 7
6
10 8
—
9 6
J
9
2
A 6
On the last diamond, West can't part with a spade or a club, so must part with a heart. Declarer then can play the ♠ A and a low spade, forcing West to lead clubs.
So the most South can make in notrump is 11 tricks.
Declared by North, though, 6 NT plays itself. Declarer can set up the two extra tricks he needs in either clubs or spades.

Spades

Declared by North, 6 ♠ stumbles when declared by North, after a club lead. The club lead breaks declarer's communication to the long diamonds.
When declared by South, 6 ♠ rolls home on any lead. For example, on a heart lead, declarer wins the ace, cashes the ♦ K, cashes the ♠ A-K, then starts running diamonds, pitching the ♥ Q then clubs, lead to:
9 8 7 5
—
—
Q J 10
Q
5
—
K 7
6
10 8
—
9 6
J
9
2
A 6
No matter when West ruffs in, South can get back to his hand with the ♣ A to finish running the diamonds.
If West tries to cut off the entries with a ♣ K lead, that sets up too many tricks in the dummy - only the heart loser needs to be pitched.

Diamonds

When South declares 6 ♦, West can lead a heart. This breaks off the entry to the long spades, forcing South to apparently lose three tricks. But that is an illusion - South can run the same strip squeeze against West which allowed him to make 11 tricks in notrump.
But when North declares 6 ♦, East cannot profit from leading a heart. Perhaps the club lead?
North wins the ♣ A, crosses to the ♦ K, and back to dummy with the ♠ K. North finishes drawing the trumps, crosses to the ♠ A, and ruffs a spade. Declarer still has the ♥ A, and comes to thirteen tricks. A two-trick asymmetry!

Post-mortem

This one is a relative rarity - two suit contracts play better from opposite sides. Usually, one side plays better in the suit contract(s) and the other side side plays better in the notrump contract.

Thomas Andrews; © 2000-2009.

Another Three-way Example

9
A Q 10 7
Q 7
A Q J 9 7 3
J 4 3
J 9 8 5
8 5 4 3 2
2
A Q 6 5 2
4
K J 10
K 8 5 4
K 10 8 7
K 6 3 2
A 9 6
10 6
Another deal with three potential strains. Game can be made in notrump, hearts, or clubs from one side or the other.

Notrump

If North is declarer in 3 NT, East can set it with a spade lead.
Declarer cannot play the ♠ K, because he will eventually have to take the club finesses, and will then lose four spades and a club. So declarer must duck, West winning the ♠ J.
Having grabbed a spade trick, West can shift to a diamond, and East/West eventually get two spades, two diamonds, and a club.
Declared by South, though, 3 NT makes. There is no way to put West in to lead diamonds.

Hearts

If South declares 4 ♥, he will have trouble after a diamond lead. We know, for instance, that if South draws trumps, he can come up with at most nine tricks, since it reverts to the notrump situation discussed above - East gets two diamonds, a spade, and a club.
So South has to score an extra trump trick. Ruffing clubs in hand is fruitless - he would be ruffing winners. So South wins the first diamond, leads a heart to the ten and leads a spade. East flies the ace and continues with two diamonds, forcing the ruff to occur in the diamond suit. The situation is:
—
A Q
—
A Q J 9 7 3
J 4
J 9 8
8 5
2
Q 6 5 2
—
—
K 8 5 4
K 10 8
K 6 3
—
10 6
Stuck in dummy, South cannot get back to his hand to finish off the trumps.
The diamond lead kills the entry to the South hand.
If North is declaring 4 ♥, however, East cannot take more than three tricks. If he leads the diamond king to kill the entry to trumps, he has just given up a trick, and declarer can simply allow West to win a trump. All other leads sacrifice either tricks or tempo.

Clubs

The 5 ♣ contracts are the easiest to follow.
With West on lead against a club game, a diamond lead immediately sets up a third defensive trick.
Any lead from East gives North time to set up a spade to pitch his diamond loser.

Thomas Andrews; © 2000-2009.

Blockage

10 3
A K J 7 6 4
Q 6 4
K Q
Q 8 7 5
9 2
J 10 9
A J 7 6
9 2
Q 10 5 3
A 8 7 5
9 8 3
A K J 6 4
8
K 3 2
10 5 4 2
This is the first part-score deal of this collection. Of course, given the North/South hands, nobody will end up in a part-score, but no game makes, double dummy.

Hearts

In the unlikely event that South is declarer in hearts, South can only make eight tricks on a diamond lead. There is no time to find a discard for the second diamond loser, and it is impossible to avoid two trump losers, two diamond losers, and a club loser.
However, when declared by North, West only gets to lead diamonds once, when in with the ♣ A. Declarer can eliminate clubs and spades from East's hand then throw East in with trumps to give up a second diamond trick at the end.

Spades

In the unlikely event that North declares a spade contract, he can take at most eight tricks. East leads a spade on opening lead, and when West gets in with the ♣ A, West also leads a spade. This kills declarer's chance to ruff a club in dummy, and the North is left with four spade tricks, two hearts, a diamond, and a club.
With South declaring spades, West might try a diamond lead. East has to duck or he gives declarer a second diamond trick, and South wins the ♦ K in hand.
South cannot afford to try to set up the club ruff immediate. Instead, he takes the top hearts, pitching a diamond from hand, and then leads the ♣ K at this position:
10 3
J 7 6 4
Q 6
K Q
Q 8 7 5
—
10 9
A J 7 6
9 2
Q 10
A 8 7
9 8 3
A K J 6 4
—
3
10 5 4 2
Should West win the first club? If he wins it, what suit does he exit in?
If West exits a trump, declarer wins in dummy, cashes the second club and exits a low diamond from dummy.
If East does not fly the ♦ A, West must win. Caught on lead at this position:
3
J 7 6 4
Q
—
Q 8 7
—
10
J 7
9
Q 10
A 8
9
A K J 6
—
—
10 5
West can't lead a club. A diamond lead gives declare an entry for a club ruff. And a spade lead gives declarer an extra spade trick. West cannot avoid letting declarer make four of the six remaining tricks.
So maybe East should have flown the ♦ A when the low diamond was led off dummy? After all, while this sets up the ♦ Q, there is no remaining entry to use it.
But what does East exit with after flying the ♦ A?
3
J 7 6 4
Q
—
Q 8 7
—
10
J 7
9
Q 10
8 7
9
A K J 6
—
—
10 5
If East leads a trump, declarer cashes two top trumps then throws West in with a third trump. West can cash the ♣ J, but then must give declare a minor suit winner, either the ♣ 10 in hand or the ♦ Q in dummy. If East leads the ♥ Q declarer ruffs high, ruffs the club, then leads the good ♦ Q off dummy, pitching his last club. West can ruff it (if he pitched his diamond) or not. Either way, he is endplayed into leading to declarers ♠ K-J in the end-position.
So, let's step back one more step, to when West won the first club and exited a trump.
10 3
J 7 6 4
Q 6
K Q
Q 8 7 5
—
10 9
A J 7 6
9 2
Q 10
A 8 7
9 8 3
A K J 6 4
—
3
10 5 4 2
What if, after winning the club, he exits a club? Declarer wins in dummy and leads a low diamond. If West wins, he is again stuck, so East must fly the ♦ A, as before. But here the ♠ 10 remains in dummy as a potential entry to that good diamond, giving declarer his ninth trick again.
Lastly, what happens if West exits a diamond? Declarer plays low, and the blockage in diamonds has its affect again. East can overtake, but has no satisfying shift, while if West is left on lead, he cannot prevent declarer from ruffing a club in dummy.
West also cannot profit from holding up the club one round - the blockage in diamonds is firmly around his neck.
The diamond suit blockage here is crucial. It does not keep the defense from taking the two diamond tricks which are rightfully theirs, but it does allow South to dictate who takes the second diamond trick, and, since the ♦ A is East's only entry, it gives declarer the tempo to set up a club ruff.

Thomas Andrews; © 2000-2009.

Back to Basics

A Q
A 10 8 4
Q 8 3 2
J 4 2
10 9 7 3
Q 9 7 6
5
A Q 6 5
J 8 6 5 4 2
K 5 3 2
J 10
10
K
J
A K 9 7 6 4
K 9 8 7 3
North/South can make 3 NT from either side, but the two minor suit games are more interesting.

Diamonds

We'll start with the easiest denomination first.
Obviously, a club lead by East will set 5 ♦ declared by North, leading to an immediate ruff. If declared by South, West can give his partner a ruff, but at the expense of the second natural club trick.

Clubs

The risk to declaring 5 ♣ is that the defense will force declarer to ruff two hearts, setting up a third trump trick for the defense.
But if East is on lead, that threat doesn't materialize. Suppose East leads a low heart. West is forced to contribute the queen, and declarer wins the ace and immediately attacks clubs. West wins, and continues hearts, but declarer can play the ♥ 8 from dummy, and East's king is forced. When West gets in with the second club, the ♥ 10 is high in North's hand.
If declared by South, however, West can profitably lead hearts. South must fly the ♥ A, with East and West allowed to keep the ♥ K-Q. Each time declarer loses a trump to West, West can lead a heart, setting up West's own long club trick.

Thomas Andrews; © 2000-2009.

Three Suits

J 6 5 3
A K Q
Q J 5 4 3 2
—
8 7
10 6 4
A 10 9 7
A K 8 4
K 10 9 2
J 8
6
10 9 7 6 5 2
A Q 4
9 7 5 3 2
K 8
Q J 3

Hearts

Against 4 ♥, the defense doesn't do itself any good to play the ♦ A and a diamond ruff, followed by a club. Declarer ruffs in dummy, promoting a trump trick in the West hand, but compensates by playing one round of trumps (drawing East's last trump) and then running diamonds, pitching two clubs. On the fifth diamond the situation is:
J 6 5 3
K
5 4
—
8 7
10 6
—
A 8 4
K 10 9 2
—
—
9 7 6
A Q 4
9 7 5 3
—
—
West can ruff with his natural trump trick, but then declarer has the rest of the tricks. If West holds off, declarer cashes the ♥ K, then finesses in spades and still only has one loser.
So the diamond ruff is not the way to go. How about trying to promote more tricks with club forces? If West leads a high club, declarer ruffs in North, and attacks diamonds. If West wins the first diamond and gives East a diamond ruff, East can continue a club, forcing a ruff in dummy, but then we are at this position:
J 6 5 3
A
Q 5 4 3
—
8 7
10 6 4
10 7
8 4
K 10 9 2
J
—
10 9 7 6
A Q 4
9 7 5 3 2
—
Q
Now, North cashes a heart and pitches a spade on a high diamond, takes the spade finesse, then forces out West's ♥ 10. The second forced club ruff did not gain a trump trick, and, South got an edge by having a club set up for him.
Okay, so say West ducks the first diamond, and wins the second, then plays another high club. North ruffs at this position:
J 6 5 3
A
Q J 5 4
—
8 7
10 6 4
10 7
8 4
K 10 9 2
J 8
—
10 9 7
A Q 4
9 7 5 3 2
—
Q
Declarer finesses in spades, and crosses to the ♥ A, then plays off a top diamond, pitching a small spade at this position:
J 6 5
—
Q J 5 4
—
8
10 6
10 9
8 4
K 10
J
—
10 9 7
A 4
9 7 5 3
—
Q
East can ruff, but it does not help the defense, which gets only two trumps.
Part of the reason club leads don't work is it establishes a club in the South hand. Look at the previous end-position if South's remaining club is a small one:
J 6 5
—
Q J 5 4
—
8
10 6
10 9
8 4
K 10
J
—
10 9 7
A 4
9 7 5 3
—
3
Now, if North leads a high diamond, East can ruff and South can only pitch one of his losers.
This is the essential asymmetry - if East leads clubs, the defense can avoid setting up a club trick in the South hand. If East leads a club, declarer ruffs in the North hand and attacks diamonds. West can now win the first diamond, give East a diamond ruff and East leads another club, West covering, dummy ruffing again at this position:
J 6 5 3
A
J 5 4 3
—
8 7
10 6 4
10 9
8 4
K 10 9 2
J
—
9 7 6 5
A Q 4
9 7 5 3 2
—
3
If declarer leads a low diamond, to set up the suit, then East pitches a club, South ruffs, crosses to the ♥ A, and plays diamonds. But now the ♦ J gives South one pitch, but not two, and if he plays a long diamond next, it promotes another trump trick for West.
There are other variations of this line to evaluate, but they are essentially equivalent.

Spades

Against spades, the defense has two natural spade tricks and the ♦ A. Any diamond ruffs will be with natural trump tricks, so that can't be the source of extra tricks. Hearts can't work. So we're back at the club suit.
If South doesn't ruff any diamonds, West has two diamonds. Setting up hearts in the South hand does not improve the situation for North. So the only choices are attacking trumps and diamonds. Trumps are risky - if East gets in with his long trumps he can run a lot of clubs.
So suppose North leads a diamond to the king, West wins the ♦ A and exits with a spade. Declarer wins the ♠ Q (East and North ducking.) We are at this position:
J 6
A K Q
Q J 5 4 3
—
8
10 6 4
10 9 7
A 8 4
K 10 9
J 8
—
10 9 7 6 5
A 4
9 7 5 3 2
8
Q 3
South to lead.
If South leads a diamond, East ruffs and continues clubs, forcing North to ruff:
J
A K Q
Q 5 4 3
—
8
10 6 4
10 7
8 4
K 10
J 8
—
10 9 7 6
A 4
9 7 5 3 2
—
3
Declarer still is angling for a diamond ruff.

Diamonds

Against 5 ♦, West has two natural trump tricks. His goal is to kill the South hand and keep him from pitching spades on long hearts. So West leads a spade, ducked by North and dummy, South winning the ♠ Q. Suppose South leads a low trump from hand (to draw East's only trump,) West forced to duck the ace to avoid giving up his second trump trick. Then declarer cashes the ♥ A-K-Q and crosses to the ♠ A and plays a heart:
J 6
—
J 5 4 3 2
—
—
—
A 10 7
A K 8 4
K 10
—
—
10 9 7 6 5
4
9 7
K
Q J 3
This is not a success for declarer - West ruffs the heart, keeping declarer from pitching more than one spade.
And if declarer tries to draw West's trumps before attack hearts, West wins a trump and continues spades.
On the other hand, if East is on lead, he can't damage declarer by leading spades. A low spade fails to kill the entry, and leading the ♠ K means that declarer only needs one pitch.

Thomas Andrews; © 2000-2009.

Major Pain

A Q 10 7 6 2
Q 7 6 3
A Q
A
K 9 8
K 9 8
J 10 6 3
J 8 3
J 5
J 4 3
8 7 5 2
10 7 6 2
4 3
A 10 5
K 9 4
K Q 9 5 4
Only South can make slam in spades, clubs, and notrump. If East is on lead against these contracts, then a heart lead sets up the heart king, and in each contract, declarer must lose a trick in spades or clubs to make the slam, at which point, the defense could take their heart trick.
On the other hand, the heart slam only makes when declared by North.
The problem is that South's hand is very shy of entries.
If South declares 6 ♥, west leads a spade. Declarer finesses the queen, cashes dummy's club ace, then leads a trump to the ten.
West wins the king, and continues spades, and now declarer is tangled up. He'd like to ruff a small club in dummy, but there is only one entry to his hand.
10 7 6 2
Q 7 6
A Q
—
K
9 8
J 10 6 3
J 8
—
J 4
8 7 5 2
10 7 6
—
A 5
K 9 4
K Q 9 5
But why is this spade lead better than a passive minor lead?
If West leads a minor, then the position ends up:
A 10 7 6 2
Q 7 6
A Q
—
K 9
9 8
J 10 6 3
J 8
J
J 4
8 7 5 2
10 7 6
4
A 5
K 9 4
K Q 9 5
Now oddly, the additional entry to North's hand makes all the difference.
Declarer plays the queen and ace of hearts, then ruffs a club in north, plays the ace of diamonds and overtakes the queen and runs clubs leading to this position:
A 10 7
—
—
—
K 9
—
J
—
J
—
8 7
—
4
—
9
5
West is caught in a positional squeeze.
Obviously, if North is declaring 6 ♥ the spade lead does not work, because it blows up the suit.

Thomas Andrews; © 2000-2009.

Denying Entries

Q 2
4 3
Q 9 7 5 4 2
8 6 2
J 8 5 3
10 6 5
A 3
9 7 4 3
A 10 7 6 4
K 8 7
10 8 6
10 5
K 9
A Q J 9 2
K J
A K Q J

Hearts

South makes 4 ♥.

Diamonds

If South declares 5 ♦, West leads a spade. If North plays the ♠ Q, East wins the ace and exits a spade. Declarer still has to lose the ♦ A, so he can't afford to play the clubs or hearts from her hand, so she must attack diamonds. West wins the first diamond, and returns a diamond, reaching this position:
—
4 3
Q 9 7 5
8 6 2
J 8
10 6 5
—
9 7 4 3
10 7 6
K 8 7
10
10 5
—
A Q J 9 2
—
A K Q J
South is stuck in his hand, and East must score another trick.
If North is declaring, East can't lead spades and keep North from winning the ♠ Q to take the heart finesse. So say East leads a diamond to West's ace, and West continues a diamond.
South plays two rounds of clubs followed by the ♠ K. East must duck to avoid giving North an entry. Then South plays a low spade to the queen, and East wins his ace, leading to:
—
4 3
Q 9 7 5
8
J 8
10 6 5
—
9 7
10 7 6
K 8 7
10
—
—
A Q J 9 2
—
A K
With East on lead, he must yield an entry to the North, or let South finesse hearts, take the heart ace, and ruff a heart to draw trumps and claim. Either way, declare ends up with 11 tricks.

Thomas Andrews; © 2000-2009.

From the Real World

9 2
10 9 5 4 2
K J 4 3
J 8
K 5
J 8
Q 9 8 6 2
10 9 7 6
7 6
K Q 3
10 7 5
K Q 5 4 3
A Q J 10 8 4 3
A 7 6
A
A 2
This deal comes from a Hungarian Teams Semifinal, and was submitted by Gal Hegedus. When played in the match, the two contracts were 3 NT by North, and 4 ♠ by South, which we'll see are the exact best sides for these two games.

Spades

If South declares 4 ♠, he can make by unblocking the ♦ A and using the ♠ 9 as an entry to pitch either a club or heart loser.
If North declares, however, East can lead a spade to kill North's entry before the diamonds are unblocked, and declarer must lose two hearts, a spade, and a club.

Notrump

If South declares 3 NT, a lead of the ♣ 10 sets it. Declarer cannot avoid losing four clubs and a spade.
But if North declares, the defense run into a blockage problem in clubs. East must lead one of his high clubs, which declarer can safely win with the ace, leaving the club jack in his hand. Then when West wins the ♠ K, the club suit is blocked:
9
10 9 5 4 2
K J 4
J
5
J 8
Q 9 8 6
10 9 7
7
K Q 3
10 7
K 5 4 3
A Q J 10 8 4
A 7 6
—
2

The Real Play

Against 3 NT, the real East chose to underlead his clubs, which turned out bad for him, and declarer was able to actually take eleven tricks when, after unblocking his diamonds, east won the first spade and failed to kill the heart entry to South's hand.
4 ♠ made easily.

Thomas Andrews; © 2000-2009.

The Miracle Combination

A K Q 9 6 3
A 5
Q 3
J 10 2
8 7 2
K 9 7 3
K 9 8 7
A Q
J 10 4
Q 10 8 4
J 5 4
9 6 4
5
J 6 2
A 10 6 2
K 8 7 5 3
This is the only example of a single suit responsible for a double asymmetry. The heart suit in isolation:
A 5
K 9 7 3
Q 10 8 4
J 6 2
does not even appear to provide a one-way guard, much less a more complicated two-way guard, but we'll find that the only way to set 4 ♠ is by a heart lead from West, while the only way to set 3 NT is by a heart lead from East.

Spades

It would appear, at first, that East could set a 4 ♠ contract with a diamond lead. Declarer plays a low diamond, West wins the ♦ K and exits a heart.
Declarer can win and draw trumps, but cannot untangle the diamond suit to pitch his heart.
The solution is for declarer to play low from dummy on the first diamond and unblock the ♦ Q when West wins the king. After winning the heart switch, declarer can draw trumps and finesse against East's ♦ J, then pitch the heart loser on the ♦ A.
What if East leads a heart? Then declarer cannot avoid losing a heart, but can keep East off lead long enough to set up his clubs to pitch his diamond loser.
For example, if East leads a low heart, declarer covers it with the jack and ducks the trick when West covers with the king. East then can never get in to lead diamonds.
If East leads the ♥ Q, declarer wins this trick, and, with the ♥ J in dummy, ensures that East cannot get back in lead via the heart suit to lead diamonds.
If South declares 4 ♠, a low heart lead holds him to nine tricks. South cannot avoid letting East win a heart trick, and then lead a diamond. He must eventually lose a diamond, a heart and two clubs.
Here the nature of the heart guard is not to provide a stopper or a trick, but to keep one opponent off lead. A "non-material" guard, to use the terminology of Kelsey and Ottlik's Adventures in Card Play.

Notrump

East/West have to get active against 3 NT, leading hearts. The notrump contract starts with eight top tricks. A ninth might be set up by leading the diamond queen to West's king and eventually finessing against East's diamond jack.
If South declares, and West leads a heart, declarer ducks and East wins the ♥ Q. Suppose East continues hearts. Declarer wins and runs his spades. ending in this position:
3
—
Q 3
J 10 2
—
K 9
K 9
A Q
—
10 8
J 5 4
9
—
J
A 10
K 8 7
On the last spade, West can't pitch a diamond. If he pitches a heart he can be endplayed in clubs, getting two clubs and a heart but forced to give up in diamonds in the end.
So he must pitch the ♣ Q. But now declare plays a low club to the king, and West wins. East/West get two more heart tricks, but declarer has the rest - the ♦ A and a club.
East cannot profit by shifting to a diamond or a club, either. The diamond lead just sets up declarer's ninth trick, and the club lead reduces to almost the same ending as above, only with one fewer club for everybody. Again West is squeezed.
West might lead the ♥ K but then declarer can set up his ninth trick in hearts!
If North declares, though, East can defeat the contract with a low heart lead. However declarer twists and turns, East will remain with the heart queen at the above end position, which means West can pitch down to a single small heart.
So now the heart suit is a guard from the other direction, and again it is a non-material guard. This time, it forces West to hold the ♥ K at the six-card end-position, and therefore causes him to be squeezed in three suits.
This heart suit is magic. Not only would you not believe that it provides a guard at all giving the placement of the cards, but it provides a guard in two opposite directions, one in a suit contract, one in notrump, on exactly the same deal!

Clubs

It seems almost anti-climactic to note the pedestrian one-sided guard provided by diamonds in a club contract.
If South declares 5 ♣, he cannot be harmed. On a heart lead, he wins and pitches two hearts on spades before attacking clubs. Only West can get in, and he cannot profitably lead diamonds. The third round of clubs provides entry to dummy's spade for South to pitch his diamond losers.
If North declares 5 ♣, a simply diamond lead by East will set declarer. Declarer obviously cannot avoid two club losers, and if he tries to run four spade tricks to pitch three diamonds, East can ruff, giving the defense either a third club trick or a trick in diamonds.

Post-mortem

Here is the heart suit again:
A 5
K 9 7 3
Q 10 8 4
J 6 2
The biggest advantage for the offense is that West is holding almost all of the values. The heart suit acts to protect declarer's advantage in two different ways, depending in the contract.
In the notrump contract, it serves to ensure that West holds the heart honor at the end position. It can only do that if West is on opening lead.
In the spade contract, the heart suit denies East a later entry when declared by North. Declarer can ensure that any heart lost will be lost to West. For timing reason, the defense must get their heart trick before attacking diamonds, but diamonds can only be profitably attacked by East. So the heart suit here works in conjunction with the more traditional diamond suit guard.
In five clubs, that diamond guard carries the full weight of the contract. It seems perverse that the non-material heart guard is necessary to make nine tricks in notrump or ten tricks in spades, but that the diamond guard alone is all that is needed to ensure eleven tricks in clubs.

Thomas Andrews; © 2000-2009.