Lennox Lewis, the last fighter to be crowned as the undisputed heavyweight champion, believes Oleksandr Usyk is a very formidable opponent for Tyson Fury.

This past Saturday night at Tottenham Hotspur Stadium, Fury retained the WBC title when he battered and stopped Derek Chisora in the tenth round of their trilogy fight.

The victory moved Fury closer to an undisputed fight with Usyk, who holds the IBF, WBO, IBO, WBA titles.

Fury and Usyk exchanged words in the aftermath of Saturday's fight.

Their respective promoters are looking to match them in the ring in early 2023.

Fury holds a significant size advantage, but Lewis cautions that it won't be an easy fight.

"I think it's going to be a great fight. Usyk is a champion, he's been [unified] champion for a little bit," Lewis told BT Sport. 

"He came to the fight and I know he was watching, feeling the energy. He's going to try and find a way to beat Tyson Fury. It's not going to be a walkover for Fury. This man [Usyk] is a champion. This man is dedicated. He puts everything into his training and his will to win."

As far as Fury's performance, Lewis felt the big man was holding back at times to get few more rounds of work. He says Fury could have closed the show at any moment of the fight.

"It was a great fight for Tyson, not for Chisora,' Lewis said. "Fury could've done anything he wanted. 

"You can tell he's got that Christmas spirit on, so he's about 80 percent of his normal self. I felt he could've stepped it up at any time and got rid of Chisora. He definitely wanted to get the rounds and the work in. That's very wise of him to recognize that. Noticing that he needs work. 

"I think the referee made the right call. It's hard for his [Chisora] corner to stop the fight at that point, but they definitely should have before the ref. The referee did the right thing."