Anthony Joshua will fight Oleksandr Usyk at the Tottenham Hotspur Stadium in September.
Joshua was preparing for a title unification bout against Tyson Fury in Saudi Arabia on August 14 but Fury was then ordered to face Deontay Wilder for a third time.
That left Joshua's promoter Eddie Hearn scrambling for an opponent for Joshua with mandatory challenger Usyk the obvious option.
The Ukranian is 18-0, and was considered one of the pound-for-pound best fighters in the world when he fought at cruiserweight, beating the likes of Tony Bellew and Mairis Briedis.
He moved up to heavyweight at the end of 2019 defeating Chazz Witherspoon before cementing his position as WBO mandatory challenger with a win over Derek Chisora last Halloween.
A deal was close to being reached for Usyk to fight Joe Joyce for an interim title while Fury and Joshua completed their two-fight deal - but Usyk will instead face Joshua at the home of Spurs, reports Sky Sports News.
Joshua last fought in December when he stoped Kubrat Pulev in the ninth round after a dominant performance, having taken a year out after retaining his titles against Andy Ruiz in Saudi Arabia.
He had planned to fight last summer, but coronavirus restrictions delayed the fight by six months.
Usyk and Joshua both won gold at the London Olympics in 2012, with the Ukranian winning at heavyweight while Joshua took the super-heavyweight honours.
In 2018, Usyk unified the cruiserweight division by defeating Tony Bellew after winning three of the four titles during the World Boxing Super Series.
He hasn't set the world alight at heavyweight so far, but his momentum has been halted by restrictions that kept him out of the ring for almost a year between his debut at the weight and his fight with Chisora.
Meanwhile, Joshua looked back at his aggressive best against Pulev in December - dropping his opponent down multiple times before a brutal knockout to the delight of his home fans.
He had looked lacklustre in his safe performance against Andy Ruiz Jr their rematch the year prior having been stopped by the American earlier in the year at Madison Square Garden in his US debut.
It is now expected that should Fury beat Wilder in their trilogy on July 24 - and Joshua deals with Usyk - there will be a unification bout in December.
