The mechanics of the ducking play ordinarily consist in conceding a trick (which must be lost sooner or later in any case) to the opponents at an early stage, conserving one or more winning cards of the suit with which to enter the hand later.
A K 8 6 4 3
7 5 2
A 7 6 5 4
8 3 2
A Q 6 5 4
If in any example the suit is established in the usual way, by taking in the available honor-tricks and then giving up a trick or tricks to establish the long cards, North cannot later cash the long cards without a side entry.
If a trick is ducked on the first round (in Figure 1), a subsequent lead by South will enable North to run the entire suit, even if they were divided 3-1 in the opponents' hands.
In Figure 2, against the expected 3-2 division, North must duck twice, taking the Ace on the third round to run the remainder of the suit.
Figure 3 is rather a desperate case, but if North has no side entry and the suit must nevertheless be brought in to make the contract, the first round is ducked entirely, and on the second round the Queen is finessed. If West had the King, and if each opponent had three cards of the suit, it will yield four tricks.
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