A small amount of extra prudence would have gone a long way for declarer on this deal from a recent tournament. South plays a contract of four spades following a simple auction of 1S-2S-4S without opposition interference.
The opening lead is the 7 of spades on which East plays the deuce. This is what declarer saw:
' K J 8 5
'* 6 5 4 3
'¶ Q J 7
'£ K 9
' A Q 10 6 3
'* A K 10 8
'¶ 6 4
'£ A 2
When the deal was played, declarer adopted a plan that was (almost) certain to succeed. He drew trumps in three rounds, cashed the high clubs ending in hand and led a diamond to dummy's Jack. East held:
' 9 4 2
'¶ A K 10 8
'£ J 7 5 4 3
Upon winning, East led his singleton heart, covered by South's eight and captured by West's nine.
West reverted to diamonds and when dummy could not take a diamond trick and the hearts failed to split 3-2, declarer went down one.
Of course, to be defeated, declarer needed to find both diamond honours offside and a very unlucky heart division - singleton seven or deuce with East or singleton nine with West.
His line of play had a probability of success in the range of 97 per cent or so.
But it was not the best. By drawing trumps, eliminating clubs and cashing one high heart prior to starting diamonds, declarer could guarantee the contract.
On the actual deal, East is immediately end-played upon winning the first round of diamonds. He is out of hearts, and has the choice either of setting up a diamond winner in the North hand or conceding a ruff-discard by playing a club.
And, if instead, East has another heart to play, declarer simply covers his card to pick up that suit with only one loser.
All roads thus lead to ten tricks for North-South.