Tyson Fury challenged Oleksandr Usyk to forego any rematch clause ahead of their proposed blockbuster bout in April - before Usyk insisted the clause was coming from Fury's side and that he does not want to play the Briton's "stupid games".
The World Boxing Association confirmed on Friday evening that an "agreement" had been reached for a fight between the undefeated pair, who hold the heavyweight division's four titles between them.
WBC champion Fury addressed WBA, WBO and IBF champion Usyk in a video posted on Twitter, saying: "I've been speaking to the lawyers and Usyk's people have been talking about rematch clauses.
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"Here's one to up the ante - how about there is no rematch clause for both of us? Let's up the ante completely.
"Never worry about what's in the future or how many more dollars you can get after you've been defeated. Worry about the fight.
"No rematch clause. Winner takes the glory, the loser goes home. How about that? Agree to that."
Usyk responded by releasing a video of his own, in which he said: "Greedy Belly [Fury]. Very much, the clause comes from your side, not mine. Stop whining and ducking.
"Be a man. Ink the contract or vacate the belt. I need undisputed - and not to play your stupid games."
Speaking last week, Usyk said a fight with Fury was "very important for both of us" and that it must be made.
"All four belts haven't been held by one person, so both of us need this fight," Usyk said, pointing out it has been two decades since the heavyweight division had an undisputed champion.
"I'm not afraid of Tyson Fury. His will be like any other fight. It's just a big man who has never lost before against a man who has the WBC belt.
"Of course it's possible to get carried away but actually this is a normal fight for the right to win all the belts.
"If a person is bigger than me, it doesn't mean they're stronger than me. If they have longer arms, it doesn't mean that it will be an advantage.
"I've been boxing since I was 15-years-old. They kept telling me that I shouldn't be boxing. They told me that I wouldn't become an Olympic champion or a world champion and that I shouldn't have switched to the heavyweight division.
"But these were opinions from people who couldn't do it themselves. Personally, I keep praying and move forward. I don't worry about whether I will reach my destination.
"It's like a samurai. He doesn't have an aim, he has his path. I have my path too."