Setting Up a Marked Finesse

Sometimes we can set up a marked finesse position.

Here, in 3NT, West opening lead was ♠Q. We could have won the trick in either hand, but West surely has ♠J. (He probably started with ♠QJ9x.) So we took the first trick with our ace, and now we have a marked finesse against the jack.

Our threat card is ♠10.

We should lead ♠2 and play ♠10 when West plays low.

If we had won the first trick with ♠K, then there would be no finesse position.