David Haye admits he will be taking "a crazy step up" when he fights world-ranked heavyweight Thomasz Bonin at Wembley Arena on 27 April.
Haye's dream is to become heavyweight world champion
Londoner Haye, 26, has made his name at cruiserwight, but insists he can become a heavyweight world champion.
"It's a crazy step up, one I can't remember any other British fighter making," Haye told Five Live Sport.
"This guy's ranked number 11 in the world and I haven't even got a heavyweight ranking."
Haye added: "I'm looking at making changes in this sport for sure.
"If you asked me when I was three years old, I'd say I'm going to be the heavyweight champion of world. I never said cruiserweight.
I haven't got time for any Miss Kylie Minogue - she should be so lucky!
"It's what I wanted to do since I can remember. I always wanted to be the main man in boxing.
"I want everyone to recognise I can beat every other boxer in the world.
"That's why I'm fighting the guy I'm fighting. I really want to prove to everyone I am the man."
Bonin has lost only one of his 38 fights - to Audley Harrison on a controversial TKO stoppage three years ago.
Haye has also lost just once, to Carl Thompson in 2004, and has stopped 17 of his 18 victims, with only Ismael Abdoul lasting the full 12 rounds last year.
In December last year, he offered to fight WBO heavyweight champion Enzo Maccarinelli, but the pair never really looked like coming together.
Haye, who is lined up to face WBC and WBA cruiserweight champion Jean Marc Mormeck in the autumn, also denied rumours of a relationship with singer Kylie Minogue.
"There is no real story there to be honest," he said. "I'm being focused on this fight 100%, I haven't got time for any Miss Kylie Minogue. She should be so lucky!"