Which winner does partner hold?

Charles Buxton, an 18th-century English brewer, philanthropist and member of Parliament, wrote, “Experience shows that success is due less to ability than to zeal. The winner is he who gives himself to his work, body and soul.” Obviously, that is not completely true. To be supremely successful in any field, you must have innate ability. To be capable, you can compete with zeal. Even then, though, sometimes you have to guess well. East faced a nasty decision on this deal from a Bridge Base Online duplicate. He was defending against four spades. After winning the first trick with his club ace and dropping declarer’s singleton king, what should he have led at trick two? South’s three-diamond rebid was either a game-try or natural, trying to help partner judge what to do should the opponents keep bidding. Here, North was happy to bid four spades given his wonderful diamonds and singleton club. He didn’t guess that the latter was duplicated in his partner’s hand. East knows that his partner has one useful card. But is it the heart ace or a high spade? If declarer’s trumps are solid, the defenders must take three heart tricks now. But if South has the heart ace, East should exit with his trump and let West push a heart through the dummy. You can see which is right, and you can guess which option I chose when we scored only 3.3% on the board! Finally, no doubt you have further noted that I also erred in the auction. I would have made five clubs if I had dropped the club king (likely) and played North for the heart queen (certain).