Tyson Fury is set to fight Oleksandr Usyk in an undisputed heavyweight showdown in Saudi Arabia.
Promoter Frank Warren said on Friday afternoon that a deal for the blockbuster bout has finally been agreed.
However, the date of the contest, which will take place in Riyadh, has not been announced.
“Delighted to finally get this fight signed,” said Queensbury promoter Warren. “This is the biggest fight that could possibly be made in our sport.
“The heavyweights always spark the imagination of the fans, and I have no doubt this will be the biggest boxing event of the century.”
Fury, 35, is due to fight in Riyadh against former UFC world heavyweight champion Francis Ngannou on October 28. His WBC belt will not be on the line.
Last month, Usyk, 36 maintained his unbeaten record with a knockout victory over Daniel Dubois in Poland.
The Ukrainian put down Londoner Dubois in the ninth round to retain his WBA, IBF and WBO heavyweight belts.
The winner of the bout between Fury and Usyk will see the first undisputed heavyweight champion of the four-belt era.
Fury is undefeated in 34 bouts since he turned professional in 2008, while Usyk has won all 21 of his fights.
Lennox Lewis is the last recognised undisputed champion in the division nearly a quarter of a century ago.
“I can’t believe that it’s happening but it is,” said Usyk’s promoter Alexander Krassyuk.
“Difficult to express my admiration for being part of the biggest heavyweight fight of the century. Respect to Tyson for his courage.”
Fury’s proposed fight with Usyk at Wembley in April fell through earlier this year and the decision to stage the contest in Saudi Arabia is likely to attack criticism given the country’s poor human rights record.
Anthony Joshua fell to his second defeat against Usyk in Jeddah last year.
Felix Jakens, Amnesty International UK’s Head of Priority Campaigns and Individuals at Risk, told the PA news agency: “Both Tyson Fury and Oleksandr Usyk should understand how this fight will be used by the Saudi authorities to project a glitzy image of the country a world away from the dark reality of being jailed for voicing your opinion, of widespread torture, unfair trials and mass executions.
“We’d like to see both Tyson Fury or Oleksandr Usyk using their platforms to speak out about human rights issues in Saudi Arabia, something the entire Saudi population is unable to do without risking jail or worse.”