Mitch Hedberg, a standup comedian, said, “I haven’t slept for 10 days, because that would be too long.”

That is a common form of humor: two apparently disconnected phrases do relate unexpectedly. But in this deal, “10” is key. When in four of a major, ask yourself what 10 tricks you plan to win. For example, in this deal from the 2015 European Open Championships in Tromso, Norway, how would you play in four hearts after West leads a trump?

One declarer had lost one diamond and three clubs, and no doubt grumbled that he was unlucky. It is true that he was, but he did not need to be unlucky – he should have had his eye on one spade, four hearts, three diamonds and two spade ruffs in the dummy.

Declarer wins the first trick with his heart eight, cashes the spade ace, ruffs a spade in the dummy, and plays a diamond to his queen, which West ducks, realizing that winning the trick cannot defeat the contract. South ruffs the spade queen, draws trumps, and continues diamonds. West takes the third round, apparently cutting declarer off from the last diamond, and leads his final spade. South ruffs and must broach the clubs.

Here, he must lead either the jack or king. West takes the trick, but has to return a club, letting South’s king or jack be his 10th trick. If, instead, South exits with a low club, he will lose three club tricks.

Probably it is best to lead the king. One indication is West’s opening trump lead, which suggests dangerous holdings in the other suits, especially the minors.