But he put up the ten and won the trick.

Does it really matter whether you win seven tricks or eight?

If a player can win the trick then they must do so.

He won the first trick in his hand with the heart jack and led the club ten.

Play then continues with the lead from the hand that won the last trick.

The player to win the trick is the one to start the next round.

South allows West to win the first trick with the heart king.

East played low and South put up the king, winning the trick.

The opening lead was the heart jack, which won the trick.

The right play, not obvious, was to allow West to win the first trick with the club king.