Anthony Joshua has "had it easy" so far in his career according to Dominic Breazeale, who he fights on Saturday at London's O2 Arena.IBF heavyweight world champion Joshua, 26, is making the first defence of his title against the unbeaten American.
Joshua, who has won all 16 of his professional fights with knockouts, has only gone beyond three rounds once.
"I think Joshua's thinking of me as a stepping stone and he's going to be sorry about that," said Breazeale, 30.
Breazeale, who is an inch taller than Joshua at 6ft 7in, is a former Olympian and is ninth in the IBF rankings, below Britain's David Haye.
Londoner Joshua, 26, won the IBF title with a second-round stoppage of American Charles Martin on 10 April.
Of his 16 fights, the longest has been the seventh-round stoppage of Dillian Whyte in December, to win the British heavyweight title.
Joshua won Olympic super-heavyweight at London 2012, in an event where Breazeale lost in the first round.
Brezeale added: "I think he's had it easy so far, fighting in the Olympics in his backyard, having the judges there in his backyard. Even as a professional, he fought a guy in Charles Martin that really didn't show up on fight night.
"Yes, he's got rid of a lot of his guys in the earlier rounds, but he hasn't been taken into deep waters. Do I want to see him go into uncharted territory? Of course, without a doubt.
"I plan on putting on some extreme pressure and taking Joshua to places he's never been."
Joshua's title defence tops the bill on a big night of British boxing at the O2.
George Groves and Martin Murray face each other in an eliminator for the WBA World super middleweight title, Chris Eubank Jr defends his British middleweight title against Wales' Tom Doran, and John Wayne Hibbert meets Andrea Scarpa for the vacant WBC Silver super lightweight title.
Whyte, unbeaten Birmingham star Kal Yafai, Olympic bronze medallist Anthony Ogogo, Conor Benn and Felix Cash are also in action.