This hand was played in team competition. Both tables bid the spade slam after West's opening pre-emptive bid of four hearts. The king of hearts was the opening lead both times the hand was played. Once again, the difference in the play occurred early on and revolved around a finesse.
At the first table, declarer won the ace of hearts and drew trumps in three rounds, ending in the South hand. He next led a small diamond. West discarded a small heart and declarer called for the queen from dummy. East won the king and returned a heart. Declarer trumped the heart return and played on clubs. When West was able to guard the club suit, declarer was forced to concede another diamond trick to East and the contract was defeated.
In the replay, declarer won the ace of hearts and trumped a heart. Spades were drawn in three rounds, ending in the South hand. A small diamond was led toward dummy and when West discarded a small heart, declarer spurned the finesse and called for the ace. Declarer won the king and ace of clubs and trumped a club. He cashed his last spade reducing the hand to the following position:
At this point, declarer led a diamond to the queen and while East could win the king of diamonds, he could do nothing to defeat the contract.
How did declarer know that this would work? He counted the hand. Look at all of the information he had available at the point in time that he led a small diamond toward the ace. He knew that East held three spades and two hearts. When West cannot follow to the first diamond, East is known to have five. That leaves three clubs. West must have four clubs and will be able to guard the club suit. With each defender guarding one of the minor suits, there is no squeeze.
The good news is that when declarer plays three rounds of clubs (trumping the third round), East will have nothing left but diamonds and can be subjected to an end play.
The moral of this hand is that you should practice counting every hand, even when you think it doesn't matter. When the going gets tough, it's good to know how many cards the defenders have in each suit.