Eddie Hearn: Alexander Povetkin will be Anthony Joshua's toughest opponent since Wladimir Klitschko

Alexander Povetkin fights Anthony Joshua later this month (Photo by Bryn Lennon/Getty Images)

Anthony Joshua's upcoming fight with Alexander Povetkin will be his toughest since Wladimir Klitschko, Eddie Hearn has warned.

The unbeaten Briton (21-0, 20 KOs) faces Povetkin (34-1, 24 KOs) at Wembley on Sept. 22 with his world heavyweight belts on the line.

Povetkin's status as a mandatory challenger has seen the 39-year-old assume outsider status for this month's fight.

However, Joshua's promoter, Hearn, has counselled against overconfidence from his charge, suggesting it will his biggest test since last year's high-profile clash with Klitschko.

"In my opinion, this fight is Anthony's toughest outside of Klitschko, and maybe even including Klitschko because of everything that's at stake," Hearn told reporters at a press conference. "We take this threat extremely seriously.

"I think this is even a tougher fight, you know, than some of the fighters that are getting mentioned as future opponents.

"So I know that ultimately this will be a great fight for Anthony Joshua to show his improvements and to show that he is the very best heavyweight in the world."