Declarers had a chance to execute this play Monday night on online bridge play:
♠ Q 7
♥ A 10 6 5
♦ A Q 10 9 8 3
♠ 10 3 ♠ K J 6
♥ J 7 3 ♥ K 9 8
♦ 7 5 ♦ 4 2
♣ K Q 10 9 8 3 ♣ A 7 5 4 2
♠ A 9 8 5 4 2
♥ Q 4 2
♦ K J 6
After West opens the bidding with 3♣, many of the 83 declarers played 4♠. How many losers are there? If they are not careful, the declarers in 4♠ could lose one club, one heart and two spades.
Suppose West cashes the ♣K at trick one. Because there is a singleton in dummy, East should give suit preference to help West know to shift to a heart. After this, it does no good for declarer to rise with the ♥A -- South can't draw trumps in time to discard his heart losers on the diamond suit. After the defense wins the first two tricks, it all depends on the play in the spade suit.
Declarer should win the return at trick three in his hand, and advance a low spade, inserting the ♠7 when West plays low. East wins the ♠J and exits. This should be won in the dummy, to lead the ♠Q -- it doesn't matter if East covers or not. The ♠Q pins the 10 in West's hand, and declarer escapes with only one trump loser.
Notice that declarer finessed West the first time the spade suit was led, then finessed East the second time. Fancy, ya? Also, note that it's a pretty safe bet that East has the ♠K because of the bidding, making the intra-finesse his best shot.
I searched the results here, but didn't see where any declarer found this play. I held the same hand, but our auction was 3♣, 3♦ by my partner, followed by 5♣ by my right-hand opponent. I might have introduced my spade suit at the four level, but not at the five level. I bid 5♦, and we made it for a 7.72 IMP pickup.
It would have been a more fun to blog about this if I had been given the chance to make the play. If you can't create great art, however, it has to be enough just to look at and appreciate it. The same with bridge.
You can read more about the intra-finesse here or here or here.