This deal was the last one played in an intermediate class on suit combinations. All four tables played in 4♥ and each defense began with three top spades.
After ruffing the third spade, three of the declarers played the trump suit correctly in isolation: ace of trumps then a trump to the queen. If East had begun with four trumps, these declarers would have made an overtrick. However, on this layout, West could ruff the third club and exit in spades if declarer had drawn a third trump or in trumps if he had not. So South lost a trump and a diamond for a one-trick set.
What happened at the fourth table? After ruffing the third spade, this declarer cashed the ace and king of trumps and, after the 4-1 break was revealed, he tried to run the club suit. West ruffed the third club but could do no better than exit with a spade. Declarer ruffed this then crossed to dummy with a trump to the queen, thereby drawing West’s remaining trump. Declarer then had ten tricks: five trumps, a diamond and four clubs.
The teacher asked the student why he had played the way he did. The declarer replied, “It was the last deal of the night and I thought that, if it were true to those in earlier classes, it would be a counter-example to what we have been studying. So, as we would have been expected to play the trumps in the classic fashion to avoid a loser in the suit, I reckoned it would turn out that West would have four trumps. If that were the case, there would be no point in making the standard play.”
The teacher replied, ‘’The reason this line works is that when West ruffs in, there is still a trump entry to dummy. Also, if it turned out that East had held the trump length, declarer would still have survived, for the same reason. So, the correct play of a suit in isolation is not necessarily the correct play on the deal.”
The full deal: