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On the actual deal, Northís 3♦ preempt got N-S to a dubious 3NT when 4♥ was indeed a superior contract. Against 3NT, the opening lead was a Spade to Eastís Ace, then a Spade to Declarerís Jack and Westís Queen, followed by a third Spade. On the second and third Spades, Dummy pitched a Club and a Diamond (a Heart could not be spared as the 4th Heart was a potential entry).
After winning the third Spade trick, how would you play the Diamond suit? Would you finesse against the Queen, or would you play for the drop?