West might have considered his double fit with partner sufficient reason to bid five hearts, which might have escaped for down two with a good guess in the trump suit. His assets were meagre, however, and he chose to take his chances on defence.
The defensive prospects were pretty good. Declarer is off the ace of trumps and at least one diamond trick, and he will have his hands full holding diamonds to one loser. South won the opening spade with dummy’s ace and led a trump to his king, winning the trick as East ducked his ace. What to do about the diamonds? All would be well if the diamonds split 2-2, but what if they were 3-1?
Should West have a singleton, declarer must hope that it is either the king or the queen and lead a low diamond to dummy’s ace followed by a diamond toward the jack. If it is East with the singleton, declarer must lead his jack, hoping East has the singleton 10. Also, the lead of the jack will put pressure on West to cover with either king-10-third or queen-10- third.
This may seem like a pure guess, but experts know that there is almost always something to guide declarer’s decision. In this case, the choice is clear. East has shown at least 5-5 in the majors and seems likely to hold ace doubleton in clubs. The only opponent who can have a singleton diamond is East, so lead the jack it is. Success!