As East, after South’s weak two spades is raised to game, you elect to go quietly in the hope of getting a plus score. Partner leads the heart five, fourth highest. How should you defend?
You can see three tricks for the defense. If partner has the heart king, that makes four. If not, you will need a second club trick, and there is a danger that declarer can score 10 of his own via five trumps, four diamonds and a heart unless you are quick about it.
Clearly, in order to make a second club trick, you will have to get partner on lead for a switch through dummy’s club king. The only card you can put him in with is the heart jack, but only if you insert the heart queen at trick one. The Rule of Eleven tells you that there are six cards out that are higher than partner’s five, and you can see only four of them, so this is perfectly safe. If partner has the heart king after all, your queen will hold.
Declarer takes the heart king and then leads a spade to the king and your ace. Now you must underlead in hearts, returning the two to partner’s jack. He should get the message that a club shift is in order; why else would you be so desperate to put him on lead? You can then take dummy’s club king with the ace and cash the club queen for the setting trick.
Playing third hand high with the heart ace at trick one lets the contract make, since declarer can ruff the third heart trick and keep West off lead for the duration.