South leads the ♦9.
East to guarantee a contract of 6NT.
Declarer wins the diamond in hand and must lead the
the defense ducks in order to prevent an immediate claim. Declarer now tries the
♥J (or ace and jack); again, a defender with four or more hearts
including the queen must duck, or twelve tricks are made available. Now declarer
plays on clubs, setting up the slam-going trick in that suit.
Trap: if declarer plays both top spades, the defense could duck. Then, when
coming on lead with another suit, the
♠K could potentially be
cashed for the setting trick. If instead declarer plays out the hearts or clubs
first, the defense can grab its winner, as there might not be enough tricks.