play one's ace
play one's trump card

His next move was to play a spade to dummy's ace.

Still unconcerned, South played his heart jack to dummy's ace and called for the club queen.

South played a diamond to dummy's ace, confident that the king would appear.

After winning the first trick with dummy's heart eight, he played the diamond queen to his ace.

South played a club to dummy's ace, uncovering the terrible division.

But South immediately played a spade to dummy's ace and could not recover.

West won and played a club to dummy's ace.

South played a spade to dummy's ace, and continued with the diamond queen.

South, sensing what was happening, played a diamond to his ace, hoping to drop the king, and conceded down one.

The declarer played to his ace and led the club queen for a finesse.