A Subtle Promotion
A K
A 8 7 4 2
10 8 4
10 7 2
Q 7 6
9 6 5
6 3
A Q J 8 5
8 3 2
Q 10 3
A K Q 7 2
9 6
J 10 9 5 4
K J
J 9 5
K 4 3
Notrump
In notrump, each side can run at least seven top tricks. East/West can
take 10 tricks by leading a diamond to the ace, club finesse, run four
diamonds, then finesse clubs again and run clubs. North/South get seven
tricks by leading a spade to the king, heart finesse, heart king, another
spade, and then running three good hearts.
Spades
Against a spade contract, East/West must get a spade, so they simply
take their six top tricks in the minors.
Hearts
Against a heart contract, East/West start the same way - diamond, club
finesse, two diamonds, club finesse, club ace, then a fourth club. East
ruffs high with the queen (or 10) and this promotes West's
♥ 9.
Diamonds
If East/West declare in diamonds, the defense takes two top spades, finesses
in hearts, cashes the
♥ K, ruffs a spade, cashes the
♥ A,
and finishes up with a fourth round of hearts, promoting South's
♦ J.
Clubs
The trickiest case is when East/West declare clubs.
North/South take their two spades, three hearts, and a spade ruff as before.
On the third round of hearts, South pitches a diamond, and, when North
leads a fourth round of hearts, South pitches a diamond again at this
position:
What should East/West do? If they ruff in East, they can only finesse
once in trumps. But if East pitches a diamond and ruff with the West
hand, they only have one entry to dummy, since South can ruff a
second diamond entry, so again they can only finesse in clubs once.