Anthony Joshua admits that he “faded” toward the end of his 12-round, unanimous-decision defeat to Oleksandr Usyk.

The former IBF/IBO/WBA/WBO heavyweight champion therefore took measures throughout his recently completed training camp to enhance his stamina for their rematch. The 6-foot-6 Joshua still isn’t sure, however, if he’ll have the requisite energy Saturday night to keep his punch output at a high enough level if Usyk takes him into the championship rounds again during their second title fight at Jeddah Superdome in Jeddah, Saudi Arabia.

“I can’t say now,” Joshua told a small group of reporters during a conference call Wednesday. “What I’ve noticed in the fights here I think is all these guys have been sparring and training, and they get to the fight and they’re f***ing blowing.

“Like it’s only like [Floyd] Mayweather, like Errol Spence, I think [Terence] Crawford, they have like phenomenal conditioning. They can work from round one to what, round 12, right? So, I don’t know how good my conditioning is. I hope it’s good. I’ll find out Saturday.”

Usyk sensed that the taller, thicker Joshua was tired toward the end of their 12-round bout last September 25 at Tottenham Hotspur Stadium in London. In fact, Usyk believes that if he had another 30 seconds to get after Joshua, he at least would’ve dropped his huge opponent prior to the final bell.

The 32-year-old Joshua believes he can knock out Usyk in their second bout. He intends to put more on his power punches, but he’ll expend more energy while trying to take out Usyk.

That’s why it was so important for the 2012 Olympic gold medalist to improve his stamina before he shares the ring again with the former undisputed cruiserweight champion. Joshua is 2-1 in 12-round bouts, but Usyk defeated him comfortably on two scorecards (117-112, 116-112, 115-113).

“How I’ve improved it is basically I could just say, scientifically, is pushing my lactate threshold up,” Joshua explained. “That’s the easiest way to describe it, is you’ve gotta push your lactate threshold up, so you can be comfortable being uncomfortable, and that’s what training’s about.”

Joshua (24-2, 22 KOs), of Watford, England, trained with accomplished American coach Robert Garcia for the first time in preparation for his rematch with Usyk. Garcia replaced Rob McCracken, Joshua’s career-long trainer, after Joshua lost to the 35-year-old Usyk almost 11 months ago.

Ukraine’s Usyk (19-0, 13 KOs) is listed as a 2-1 favorite by Caesars Sportsbook to win a rematch that’ll headline a Sky Sports Box Office pay-per-view show in the United Kingdom and Ireland (£26.95) and a DAZN stream in the United States.

Sky Sports Box Office’s coverage of the Usyk-Joshua undercard is scheduled to begin at 6 p.m. BST. DAZN’s coverage is set to start at 1 p.m. ET.

Keith Idec is a senior writer/columnist for He can be reached on Twitter @Idecboxing.