American heavyweight boxer Deontey Wilder has stated the reason for Anthony Joshua's back-to-back defeats to Oleksandr Usyk.

The former WBC champion believes the British-born Nigerian boxer has a stamina problem which caused his defeats against the Ukrainian.

“I just felt he was very cautious,” Wilder told the BBC.

“For me it looks like he has a real serious stamina problem. I feel like he didn’t want to exchange a lot because of that.

“It allowed him to fall back a little bit and not allow him to throw certain punches and combinations.

The 36-year-old believes that boxing fans could've seen a better version of the former two-time heavyweight champion, Joshua, if not for his stamina.

“I think if he fixed that you would see a better Joshua, not just in that fight but in fights to come.

“I know if he’s able to get everything together, stamina and all that, I think you’ll see a different Anthony Joshua.”

Wilder and Joshua were in talks about a possible bout in 2019 and 2020 when both fighters were still champions.

WDN