Source: Asociacion Española de Bridge
Problem 1: Dealer: South N/Vulnerable
* 1 de 5 keycards
** Trump Quenn asking
*** I have it, and I dont have Kings
First Trick: J, Q,K,A…how do you play? The fact that you escaped from a trump lead, and that you have all the high trumps, allows you to play a «crossruff» technique: you can make 4 trumps from your hand, and 4 trumps from dummy, plus 4 honors: A, A and K and A for a total of 12 tricks.
However, you must take a simple precaution before starting to ruff: : play first Ay K, to avoid a possible discard of diamonds by a defender, then you wont be able to gain tricks with them.
The correct line is: win with the A, play A and K, and A and then begin the cross ruff.