Wladimir Klitschko will face Anthony Joshua at the Wembley Stadium on April 29 and the Ukrainian admits it is his toughest test.
Klitschko used to be the world’s No. 1 heavyweight for more than a decade, but will be challenging Joshua for his IBF belt and the vacant WBA ‘super’ titles.
The attendance at Wembley is expected to be 90, 000, which will overshadow the amount of spectators that has ever seen Klitschko fight.
“I had maybe 40,000, 50,000, 60,000 but never 90,000,” he told TalkSPORT.
“It’s the toughest challenge I’ve ever had, because in a certain way he is a copy of me size-wise and he is a world champion in a professional sport.”
Klitschko has also not ruled out the possibility of the undefeated British boxer dominating the division.
“This fight is definitely something we are thinking is going to be great on both sides,” said the 40-year-old.
“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.”