An Unblock & a Crocodile
This deal is from the 2024 Vanderbilt final:
| Vul:None Dlr: East |  108 9 KQ94 A98764 | |
| A963 J1076 J83 103 | 75 K85 A10762 QJ5 | |
| KQJ42 AQ432 5 K2 |
| West | North | East | South |
|---|---|---|---|
| Pass | 1 | ||
| Pass | 1NT | Pass | 3* |
| Pass | 4 | All Pass | *5-5 Inv. |
It was written up and discussed, but not completely enough.
In 4, Bobby Levin received a diamond lead to the king and ace.
The defense accurately switched to a spade to the ace and a second spade won in dummy.
A heart to the queen was followed by the A. East needed to unblock the king, but failed to (more on this later).
Now, declarer accurately read the position. He drew the remaining trump and played the K, A and another club. If East still had the K, declarer could ruff and play a heart. East would win and have to give dummy access to the rest.
East saw this coming and belatedly parted with the K (as declarer drew trump). But Levin found an elegant answer. On the 3rd club, he let East win, and East had to play a diamond to the dummy (declarer throwing his hearts).
So, East's only way out was indeed to unblock the K under the ace -- and keep a heart for the endgame.
The Daily Bulletin called the K unblock "double-dummy" but I disagree.
West should have helped. On the A, he has the spots to play the J to alert his partner to the need to unblock. East now knows to throw the K under the ace, leaving:
| Vul:None Dlr: East | -- - K94 A9876 | |
| 96 107 J8 103 | -- 8 10762 QJ5 | |
| KQJ 432-- K2 |
Now declarer draws trump and plays K, A and a club. He can't leave East on play (East still has a heart).
So declarer ruffs the club and exits with a heart.
Now the aforementioned Crocodile. West must swallow his partner's 8 by rising with the 10. If he plays the 7, East wins the 8 and has to give dummy access. Theoretically, the odds are 2:1 that declarer has the 8, so can West get this right? If playing "Standard" Count signals, then East's other card is sure to be the 8 (he would have played the 2,3 or 4 on the first round with an original holding of K5x).
The final word: What if East plays the 8 on the first round of the suit? Maybe they play upside-down count, so he falls into it. No humans I know are good enough to anticipate the entire Crocodile theme and unblock the 8 (and later the king) to take West off the guess in the endgame.