Former two division champion David Haye is backing Anthony Joshua to score a big knockout victory over Oleksandr Usyk.

Usyk, a former undisputed cruiserweight champion, will challenge Joshua for his WBO, IBF, WBA, IBO heavyweight titles at Tottenham Hotspur Stadium on September 25.

Haye was managing the career of Derek Chisora last October, when the heavyweight veteran suffered a very competitive decision loss to Usyk.

At cruiserweight, Usyk captured every major belt and defeated all of the top players.

Haye himself was a unified cruiserweight champion when he made the decision to move up to heavyweight - where he eventually captured a world title.

Haye believes Usyk is too small, and has the wrong style, to overcome a big physical specimen like Joshua.

"I think his style might be very effective if AJ was 6'2" and 14st," Haye told Sky Sports.

"But AJ isn't. AJ is 6'6" and he's an absolute specimen, and he's one of the best athletes ever in the heavyweight division. That just spells knockout defeat for Usyk. If Usyk was the future of the heavyweight division and he's going to be good enough to beat AJ, he should have at least stopped Derek Chisora or won by a landslide.

"But he didn't. He wasn't able to keep the heavier man off him. He didn't have the firepower. I just don't see AJ having any problems. I'll tell you exactly what punch it's going to be - a jab, right hand and then a straight jab again. The jab will knock out Usyk. He will knock Usyk out with a jab.

"He may have as much skill as I have, he may have more skill than me. But he just doesn't punch hard enough to keep the big men at bay. You can be as fast as you want, but the speed isn't bothering the big guy. Usyk's power and speed didn't bother Chisora. To beat the big men, the big monsters at heavyweight, you have to have a big punch to get their respect, keep them off you. He doesn't have the firepower to keep the big men off him, so the big men are going to be on him when they choose to."