West led the eight of diamonds and when declarer put up dummy’s ten it held. His next move was to cash the ace of spades, on which West discarded the four of clubs. Declarer continued with dummy’s two of spades but East did not go in with an honour and now declarer realised he was in trouble. He tried to cash two diamonds, but East ruffed the third round, cashed the king of spades and switched to a club, one down, -100.
Declarer was unlucky that spades were 5-0 – but having been gifted a trick on the lead starting with dummy’s two of spades is a sure tricks play.
Here West led the six of diamonds and once again declarer won with dummy’s ten. His next move was the two of spades, which left East with no good move. preserving the extra entry in spades meant declarer could play as if he were in no trumps, losing only two trump tricks and a club.
Doubtless you will have observed that if West leads a heart, not surrendering a trick the contract must fail.