It happened in our online training on 6th Nov,2017. It seemed to be a normal game contract to defender, however it was easy to fall into declarer's trap. Board 13 Both Vul West North East South 1♢ 3♠ Pass Pass 3NT AP 3NT North Trick 1 2 3 4 1 ♠T ♠7 ♠6 ♠J 2 ♢9 ♢4 ♢Q ♢3 3 ♡Q ? East leads the ♠T and the declarer wins the ♠J in hand. Then declarer plays ♢9 to Dummy's ♢Q. After that, the declarer plays ♡Q from table quickly. How to play? It seems that declarer holds ♡A. It is common knowledge that K should be played on the second trick to prevent partner's T from finesse on the next trick. Does common knowledge work well in this deal? East plays ♢4 on the second trick, indicating that East holds odd cards in diamond. Obviously, Eas