North dealer. East-West vulnerable.
Opening lead — two of diamonds.
Ordinarily, a player is declarer in one deal out of four, dummy one deal out of four, and a defender two deals out of four — which means that a player is on defense twice as often as he is on offense. Despite this obvious fact of bridge life, the role of a defender does not receive anywhere near the attention it deserves.
To defend well is surely as important as playing the dummy well. Consider this deal which illustrates the kind of challenge a defender sometimes meets. South is in four spades and West leads a diamond. East wins dummy’s king with the ace and must decide what to do next.
His proper return is the four of trumps, after which declarer must go down; with any other return, declarer gets home safely. Moreover, East should work out that the low trump return at trick two offers virtually the only chance to defeat the contract.
East should reason that West’s deuce of diamonds lead, presumably his fourth-best, marks declarer with three diamonds, all losers. East also knows from the bidding that South must have both missing aces as well as the king of spades. So it would be futile for him to play the ace and another spade to try to stop a diamond ruff in dummy.
Indeed, declarer would make the rest of the tricks against that defense. Only by maintaining control over trumps can East hope to stop the contract. He can’t be certain that the spade return will defeat the contract, since that depends on how the unseen cards are divided. But he can determine that the low trump return offers the only realistic chance to score three diamond tricks and put the contract down one.