The club queen was led and covered with the king.

West led the club queen, which seemed safe but was not.

East would not have passed throughout with the club queen as well.

The club queen would then be sure to fall, from one side or the other.

Instead, South did better by leading the club queen from his hand.

West failed to see the need to drop his club queen under the king, a very difficult defense, and South was now in control.

South therefore played for West to have the club queen and made his game.

That could be essential if West held the club queen instead of the king.

But West made the normal lead of the club queen.

He won the first trick with the heart king, and led the club queen.