Defend along with Steve Weinstein as West in this deal from the 2025 Spingold Teams championships.
Using a style where partner’s double of four spades shows a good hand rather than being a pure takeout double, you elect to pass. (Incidentally, I would bid five hearts if I thought we had a good chance to make it — especially if we were vulnerable.)
Having done that, you choose to lead a club, specifically a third-and-fifth club five. Declarer plays low from dummy, and partner wins with the king before shifting to the heart king. How should you defend?
It is easy to switch off on hands like this, but the danger is clear — declarer is marked with the club jack after partner’s play of the king at trick one, so he will be able to discard whatever diamond losers he has on clubs. Your only chance is to get a diamond trick going right away, before declarer can draw trumps. In case partner has the diamond king and declarer the queen, such that the switch must come from your side, you should overtake with the heart ace to play a diamond through.
This is exactly what Weinstein did. Declarer had little choice but to play low — he needed two discards, and trying to run clubs would only work if someone had three clubs and the singleton spade ace. Thus, the contract was sunk, for a nice pickup when the East player at the other table took it upon himself to shift to a diamond at the second trick, letting four spades come home. (Incidentally, might East have made his partner’s life easier by shifting to a low heart?)