Anthony Joshua has reached an agreement with Tyson Fury on a two-fight deal, says promoter Eddie Hearn.
Talk of an undisputed megafight between the two British heavyweights has been on the cards since Fury, 31, scored a sensational seventh-round stoppage over Deontay Wilder in March to claim the WBC title.
Joshua, 30, regained the WBA, IBF and WBO belts with a unanimous verdict over Mexican-American Andy Ruiz Jr in Saudi Arabia in December.
Hearn, the head of Matchroom Boxing who promotes Joshua, said although no contracts have been signed both fighters had agreed financial terms in principle to a two-fight deal with the first slated for 2021.
"We're making great progress," Hearn told Sky Sports News. "There is still a lot to overcome. We are looking at venues and dates."
Joshua's next fight is with mandatory IBF challenger Kubrat Pulev, but their bout scheduled for June 20 was postponed due to the Covid-19 crisis. Fury will take on Wilder for a third time later this year after the American activated the rematch clause inserted into the contract from the second fight.
Another British heavyweight contender, Dillian Whyte, is due a mandatory shot at Fury's belt by February 2021.
"The biggest fight in British boxing history has just been agreed. Two-fight deal. Tyson Fury versus Anthony Joshua next year," Fury said on Instagram.
"I've got to smash Deontay Wilder's face right in in my next fight and then we go into the Joshua fight next year."
"It's fair to say [Joshua and Fury] are in agreement regarding the financial terms of the fight," Hearn added.
"We've been talking to [Fury's management team] MTK, giving them the assurances from Joshua's side that all the details on the structure of the deal is approved from our side. And it is from Fury's side, as well.
"We're in a good place. It's fair to say that, in principle, both guys have agreed to that fight. Two fights.
"[There's] a lot to overcome in the meantime. We're moving in the right direction. I'm confident that both guys have given their blessing for the fight to go ahead.
"The point of Fury, Joshua and the teams agreeing to the structure of the deal? The first fight could happen next summer. It will be 2021."
Asked about a possible location for the Joshua vs Fury fight, Hearn added: "There are discussions with various sites.
"From a common-sense point of view and without knowing how a deal works, everyone will say Britain is the place to hold the fight. But it is the world heavyweight championship - there will be all sorts of offers from across the world, and there have been already.
"The venue is another obstacle to overcome."