Source: “Watson the Play of the Hand at Bridge” Chapter XI, Page 105 One rather unusual type of ducking play involves the deliberate refusal of a finesse.  Let’s say that West’s opening lead against your three no-trump contract is the four of Diamonds.  How should you play this hand?
A 8 7 6 4 7 3 2 9 8 10 6 4
K 10 5 10 9 6 J 10 5 4 2 K J 9 3 Q J 8 4 A 7 6 Q 8 5 2
Q J 2 A K 5 K Q 3 A 9 7 3
Answer: East wins with the Ace and returns the seven, which you win with the Queen.  You have six winners off the top (1 Spade, 2 Heart, two Diamonds, and 1 Club).  Obviously you need to set-up three more Spade tricks.  You lead the Queen of Spades and West covers with the King.  What do you do now? If you cover with the Ace of Spades, you will be cut off from the board.  You must duck this trick to set-up dummy.  When you return to your hand, take the Jack of Spades and lead the two toward your Ace.