West could see that his best chance to win the setting trick with the king of diamonds was to put the dummy in, so that South could try a finesse. West therefore tossed his spade ten on the ace, hoping that South would use this opportunity to enter dummy with the spade eight.
South did not stop to question the motive of West's play. Seeing a free entry to the dummy, he led a low card to the eight of spades, discarded a diamond on the jack of hearts, and then took the diamond finesse. West won with the singleton king and defeated the contract. If West had kept the ten of spades, South could not have entered the dummy and would have had to lead his ace of diamonds.
Text read from the printed page and cleaned; old type leaves the occasional error.