Harrison (left) did damage with his left uppercut

Audley Harrison won his ninth professional fight after his American opponent Rob Calloway retired at the end of the fourth round.

Harrison had begun to dominate the fight after an indifferent start to the contest and in the fourth round, the British fighter landed a left uppercut which apparently broke the American's jaw.

Watch the climax of Harrison v Calloway

For the first two rounds, Calloway's movement and sneaky right hand troubled Harrison, who appeared reluctant to commit himself to the attack.

But his size and jab began to take over in the third round as Calloway started to tire.

The American had never been stopped before in a career spanning over 50 fights, most of which were contested at light heavyweight and cruiserweight.

Harrison remains unbeaten after nine fights and intends to return to the ring on 29 March at Wembley.