In the card game of contract bridge, the holdup play is often beneficial when playing notrump contracts.
S: J 10 7
H: 10 8 3 2
D: A 5 3
C: K J 10
S: Q 9 6 S: 5 4 3 2
H: 7 5 4 H: Q J 6
D: K Q J 10 9 D: 7 4 2
C: 8 3 C: A 7 4
S: A K 8
H: A K 9
D: 8 6
C: Q 9 6 5 2
South is playing a contract of three notrump, and West leads the king of diamonds. South has the nine tricks she needs: two spades, two hearts, one diamond and four clubs. However, if she wins the ace of diamonds at trick one and drives out the ace of clubs, the defenders will cash four diamond tricks to set the contract.
South can assure her contract (provided the ace of clubs is with East) by holding up her ace of diamonds: she plays low to the first two diamond tricks
(known as ducking) and wins the ace of diamonds on the third trick. Now, when East wins the ace of clubs, she has no diamonds left to play. If West holds the ace of clubs, the contract is impossible to make.
Rule of Seven
Take the number of cards you hold in the defenders' suit, subtract from seven, and duck that many tricks.
In the hand above, there are five diamonds in the combined North-South hands, and declarer must duck two tricks (winning the third).
If there were an additional diamond in either the North or South hand, for a total of six, then declarer need only duck one trick (winning the second). This is because if West has five diamonds (and North-South six), then East will have only two and will be out of diamonds after two rounds of the suit. If East does have three diamonds, then West will have only four and the defenders can cash only two additional diamond tricks (for a total of three) upon winning the ace of clubs.
This rule, of course, assumes you are playing in 3 NT. It can be generalized for all notrump contracts as follows:
Take the number of cards you hold in the suit, subtract the rank of the contract, and subtract from 4.
