If you want to make more tricks when playing duplicate, you need to take a lot of finesses. Everyone knows about simple finesses when you have an ace-queen combination and are missing the king.
The key is to lead from opposite the ace-queen. After the opponent playing second to the trick plays a low card, you assume that opponent has the missing king, so you try the finesse by playing your queen.
When your suit has the ace, queen and ten together in one hand, you have the possibility of trying a double finesse.
The correct play when the partnership has eight or fewer cards is to lead from opposite the ace-queen-ten.
After the opponent playing second to the trick plays a low card, you assume that opponent has both the missing king and jack, so you finesse the ten.
A quarter of the time, the opponent playing second to the trick will have both the king and jack so your ten will win.
Example: You are the declarer in 4♠ and your trump suit is ♠AQ10753 in north and ♠82 in south. Lead ♠2 from south. When west plays ♠4, you play ♠10.
If ♠10 wins, you can cross back to south in a different suit then lead ♠8. When west plays ♠J, you finesse ♠Q. Now play ♠A to bring down ♠K when the suit divides three-two. You make all the tricks.
What if ♠10 had lost to ♠K when you tried the first finesse? You have lost ♠10 to ♠K which is better than losing ♠Q to ♠K. Regain the lead to win ♠A and ♠Q, drawing the opponents’ spades when the suit divides three-two.
What if ♠10 had lost to ♠J when you tried the first finesse? Regain the lead, then cross to south in a different suit to lead ♠8. If west plays low, finesse ♠Q. Now play ♠A to bring down ♠K when the suit divides three-two.
A quarter of the time, your first finesse of ♠10 will lose to east’s ♠J and your second finesse of ♠Q will lose to east’s ♠K.
There is no way to avoid losing these tricks if east starts off with three or more spades including both ♠K and ♠J. Don’t be put off trying the double finesse next time. On some hands the suits are distributed so you always lose two tricks.
If your partnership has nine or ten cards, you should not try the double finesse. When your opponents have four or fewer cards, you try the simple finesse. Lead from opposite the ace-queen and finesse the queen.
If the queen wins, you next play the ace. If the suit divides evenly, you may win all the tricks when you play the ace on the second round.
Example: You are the declarer in 4♠ and your trump suit is ♠AQ10753 in north and ♠862 in south. Lead ♠2 from south. When west plays ♠4, you play ♠Q.
When ♠Q wins, now play ♠A. If the suit divides two-two, ♠A will bring down both ♠K and ♠J.
Note that with the ace and queen in separate hands, there is no finesse. It is usually best to win the ace first and see which cards fall.
Example: You are the declarer in 4♠ and your trump suit is ♠A10753 in north and ♠Q862 in south. Do not lead ♠Q. If south has ♠K, south will cover ♠Q and you take ♠A, which leaves you in danger of losing two tricks to ♠J and ♠9.
Much better is to play ♠A on the first trick and see what falls. If ♠K or ♠J falls you will have a clear picture of the suit. If you see the opponents’ ♠4 and ♠9 on the first, the second round will reveal the opponents’ honour cards.
© 2022 John Roberts