In contract bridge and similar games, a finesse is a type of card play technique which will enable a player to win an additional trick or tricks should there be a favorable position of one or more cards in the hands of the opponents.
(More precisely, the king is set up as a winner, but that doesn't mean it will necessarily take a trick.
North-South will take two spade tricks if West has either the king or the queen, or both (probability about 75% in the absence of any information), but only one if East has both (25%).
However, this combination lends itself to an endplay - if one can be effected two tricks are guaranteed.Similarly, a triple finesse is possible, and occasionally desirable, with a holding such as A-Q-10-8.
This would be a low-probability desperation play if four tricks are needed in the suit, but two or three will probably be made.
A deep finesse is a maneuver that allows additional tricks to be won, but only if two or more cards are favorably positioned.
"Deep Finesse is also the trade name of a commercially marketed computer program that performs double dummy analysis of bridge play problems.
A spade is led from the North hand; if East plays low, a diamond is discarded and the lead is repeated.
In the example at right, if South begins by leading the king-queen, he learns on the second trick that East has no more spades and so the finesse of the ten is proven.
Start by playing the king of spades (or if in dummy, leading the 2 to the king) and then running the jack; this makes three spade tricks if East has the singleton queen or if West has the queen, and if that's not the case, then East will be on lead.
Or start with the ace and 10, making three tricks in the opposite situation, or leaving West on lead.
After the opening lead of a diamond, he wins the ace and plays the two top trumps; they break 3-2.
However, the contract is cold as long as trumps break 3-2 and the defense cannot get an early ruff.
If North does play the king, declarer ruffs and later pitches a diamond on the jack of spades.
This is the classic example: NW ES Against South's 4♥ contract, West leads the ♠K, removing an entry that might have proven useful later.
The reason for the term Ann Gallagher finesse is found in a New York Times article.
She enjoyed bridge, and when she won a two-way finesse she would repeat it in the opposite direction, saying "Now let's see if I'm really lucky.
A free finesse occurs when an opponent leads a suit, so that the hand containing a tenace position plays last to the trick.
the normal finesse only works if West has the king, but if East leads spades, the declarer simply plays the lowest card that will win the trick, and so gets two tricks no matter whether East or West has the king.
North-South will take 3 spade tricks for certain, and declarer need not guess which way to finesse the suit.
Instead, in the backward finesse South, begins by leading the jack from hand and passes it if West plays low thereby scoring all three tricks in the suit.
In the first diagram, the declarer must lead a small card from hand towards the dummy's jack for an "indirect" finesse.
In the third diagram where declarer also requires three spade tricks, he must first lead low to the dummy's 9, losing to East's 10.
Next, the ace drops the jack, and leaves a simple-finesse position against East's queen in the third round.
Note that this maneuver will work with any doubleton honor with West, but will cost if West holds QJx, Q10x, or J10x A pseudo or "Chinese" finesse presents a declarer's deceptive move to fake a high-leading finesse by leading an unprotected honor, hoping that the defender will misread the situation.
However, in the alternative situation: If South leads the queen and West ducks, the declarer will lose only one trick in the suit instead of two.
This specific case of a free finesse is important enough to have its own name (after the city of Bath in England).
The Official Encyclopedia of Bridge lists suit combinations and how best to play them depending on how many tricks are needed.