Anthony Joshua said that WBO mandatory challenger Oleksandr Usyk will ‘definitely’ step up when the pair meet.
The two heavyweights will fight on September 25 at the Tottenham Hotspur Stadium, with both fighters having expected to be fighting elsewhere only a couple of months ago.
Joshua seemed set for a clash with Tyson Fury in Saudi Arabia to decide who would emerge as the undisputed heavyweight champion, while Usyk was waiting for that to resolve itself with an eliminator bout against Joe Joyce.
Speaking to Sky Sports, Joshua appeared to first skirt over Tyson Fury dropping out in order to fight Deontay Wilder for the WBC belt - a fight that has since fallen apart, for now at least.
"I don't want to point any fingers. I was definitely ready. We move forward,” he said.
"I've got another challenger who's good, just as good.
"I have to be serious about him now.”
However the IBF, WBA and WBO champion then appeared to aim a dig at Fury’s failure to make the planned match-up.
"He will definitely step up, he will definitely take the fight. That's what I need - people that are serious,” he said.
"I would have loved to have boxed for the undisputed championship because it was a big fight for the public. We had everything set up.
"I have to move forward and not keep dwelling."
Joshua remains optimistic that he will have the chance to one day fight for the undisputed title, saying: "The most important fight for me is the next one but you have to have a vision of where you want to get to.
"I have to stay consistent and stay ready.
"Once I fight Usyk, who knows what will happen next?
"Will I fight Fury, Wilder, Dillian Whyte, Andy Ruiz, Luis Ortiz? Who knows.
"I have to stay on track and ready for each fight, but have a long-term plan.
"It's about the belts, not the person. I don't mind who it is. I want to fight for legacy."