Wladimir Klitschko ready for 'toughest challenge ever' against Anthony Joshua at Wembley

Ticket sales for Joshua-Klitschko broke Wembley box office records. Richard Drew/AP

Wladimir Klitschko has claimed that fighting Anthony Joshua in front of 90,000 fans at Wembley represents an "upgrade" to his storied career.

Former world champion, Klitschko -- who reigned for almost a decade before being beaten by Tyson Fury in November, 2015 -- faces Joshua for the Briton's IBF title as well as the vacant WBA and IBO belts on April 29.

There is a huge appetite for the fight, with tickets selling out in a matter of hours of going on sale last month.

"I'm happy about it, because for me it's an upgrade in my career as a fighter, to fight on my biggest stage that I've ever had in front of 90,000 people," the Ukrainian told TalkSPORT.

"I had maybe 40,000, 50,000, 60,000 but never 90,000. It's the toughest challenge I've ever had, because in a certain way he is a copy of me sizewise and he is a world champion in a professional sport."

Klitschko is vastly more experienced than his British opponent, having fought 50 more professional bouts, winning on 64 of the 68 times he has stepped inside a ring.

Despite his inexperience, though, Joshua has won all 18 of his contests within the distance and has been tipped to enjoy a similar period of dominance if he emerges from Wembley victorious.

"This fight is definitely something we are thinking is going to be great on both sides," Klitschko said.

"One Olympic champion is fighting another one, one generation is fighting another generation, so there are a lot of questions.

"Do I still have it? Is Anthony good enough now? All these questions are in our minds. But we never thought it was going to be that big.

"Thankfully, it is that big, and it's getting even bigger, unexpectedly it's getting even bigger, and the interest is tremendous and amazing."