Sergey Kovalev stopped previously unbeaten champion Nathan Cleverly in the fourth round to win the WBO light heavyweight title in a stunning result on Saturday.

Kovalev (22-0-1, 20 KO) dominated the fight from the opening bell and sent Cleverly (26-1) to the canvas twice in a third round in which the champ barely survived. The Russian challenger kept landing damaging blows in the fourth, including a right hook that again knocked Cleverly down and prompted referee Terry O'Connor to stop the bout 29 seconds into the round.

Cleverly was making his sixth defense of the belt he won via a unaminous decision over Nadjib Mohammedi in December of 2010.