Marked Finesse

A "marked" finesse is a finesse made obvious by the auction or play of the hand.

		Dummy
		AT5
		8542
		QJ3
		JT5
		South
		KJ3
		AT
		AKT42
		Q76

West 21 Pass		North Pass 3NT		East Pass All Pass		South 2NT
1 Weak two

West leads the K against 3NT. South can count 1 heart winner, 5 diamond winners, and 2 spade winners. The 9th trick must come from either spades or clubs.

While it may seem plausible to lead clubs twice to establish a club winner, it's better to simply play West for the Q. Based on the auction, West should have six spades, leaving East with a singleton. Accordingly, South can cash the K (in case East pops up with the singleton queen) and lead a spade toward dummy for the "marked" finesse of West's queen.

The full deal:

		North
		AT5
		8542
West		QJ3		East
Q98764		JT5		2
KQJ				9763
5		South		9876
942		KJ3		AK83
		AT
		AKT42
		Q76

Had South mistakenly led a club instead, the contract would go down. East would win the K, put West in with two hearts, and then regain the lead with the A. The 9 would be the setting trick.