Source: Times Daily – 19 Oct 1982

Dealer West All Vul

A 10 8 3
9 5 4
A K J 10
Q 10 7 2
K 5
9 8 6 4
A 9 6 5
7 4
A 8 7 2
7 3 2
8 4 3
Q J 9 6 2
10 6 3
Q 5
West North East South
Pass 1 Pass 1
Pass 3 Pass Pass

Opening lead: K

It is said that a fine declarer plays as though he sees through the backs of the cards. Slightly exaggerated, perhaps, but a fine declarer actually does do well to the long run because he reasons well — and not because he has magical powers beyond the reach of plain ordinary folks. Let’s study this deal where South is trying with might and main to make three miserable hearts.

West leads the K-Q-J of diamonds. East playing the 8-2-7 in that order and shifts to the deuce of spades.

It is clear that it East has the A-Q of spades it makes no difference whether declarer plays the jack or king from dummy. The contract goes down in either case.

It is also clear that if West has the ace, the king is the right play, if West has the queen, the jack is the right play.

How does South resolve such a problem?  Superficially, it seems that which card to play is a toss-up, but it is at this point that declarer brings his analytical into play.

He sees that he cannot make the contract, whatever he does, if the trump finesse he plans to take fails. South therefore mentally assigns the king of hearts to West. To assume otherwise would be conceding defeat. Declarer then says to himself that if West had held the K-Q-J of diamonds, as well as the king of hearts and ace of spades, he would surely have opened the bidding as dealer.

Therefore, reasons South, “I am forced to assume that West does not have the ace of spades and that East must have it. He therefore plays the jack of spades from dummy at trick four and eventually makes the contract.