West opened One Club and North (who might have cue-bid his opponent's suit) doubled. East passed and South had his first serious problem. As he was forced to reply, should he show his major suit or keep the bidding as low as possible?
He chose One Diamond but found himself back in the hot seat when West bid Two Clubs and North (belatedly) cue-bid Three Clubs. Now what?
Reluctantly South showed his spades and was relieved to be able to pass when North jumped to game in diamonds.
West led 2A against Five Diamonds and switched to a low spade. Taking stock, declarer decided that West was likely to hold !K for his bidding but that #Q was by no means sure to drop. He could afford to lose a diamond trick and might well need an entry to hand in the trump suit.
Accordingly, at the third trick South cashed #A and, when nothing untoward happened, continued with a low diamond. Whether he lost an unnecessary trump trick or not, South could win the third round of trumps in his own hand. After a successful heart finesse he still had a trump left to ruff a heart and establish the suit.
If declarer had tried to drop #Q, he would have lost the contract. He would not have been able to reach his hand without playing a fourth round of trumps and then East would have come to the eight of hearts for the setting trick.