This deal was (mis)defended on the final board of a Round of 32 match in the 2022 Vanderbilt. A well-known expert was on a team that was leading by 4 IMPs heading into this last deal:

				NORTH 974 J108 Q5 AQJ42
WEST K86 KQ9 AJ86 973

South opened 1 and West reasonably doubled. This was redoubled and East bid 2. This was passed around to the redoubler (North) who bid 2 (non-forcing). East competed with 3 and South jumped to 4. West led the A and got an encouraging signal. He continued diamonds and declarer ruffed partner's K.

Next came a low heart, West winning the Q. Now what?

The defense has 2 hearts and a diamond for sure. If partner (unlikely) has the K, you will set the contract. But, if declarer has it, clubs are running. Trying to set up a spade trick (maybe partner has the Q), West switched to a spade. Wrong! This was the Real Deal:

Vul:None Dlr: South	974 J108 Q5 AQJ42
K86 KQ9 AJ86 973					1052 43 K107432 85
				AQJ3 A7652 9 K106

Declarer won the spade shift and played more hearts, taking 5 clubs, 2 spades and 3 hearts for the contract. He threw the other spade losers on dummy's clubs.

For West, this should have been a matter of counting tricks. Even if declarer had the K, he'd have only 5 clubs, 3 hearts and a spade. (Declarer couldn't have 6 hearts based on both the bidding and the play). Surely, with 6 hearts to the ace, declarer would not start with a low heart from hand. West should have gone passive with a club play and never touched spades. This would have resulted in down one and a win of the match.

As a side note, I am surprised this pair didn't play weak jumps after the redouble (3 by East) -- a popular expert treatment.

At the other table, West led a club and never played spades, so the contract was down one. The team benefitting from this misdefense went on to win the event!