Kubrat Pulev will fight champion Anthony Joshua in a world heavyweight title bout in London on 12 December, the Bulgarian claims.
Briton Joshua was originally scheduled to fight Pulev, 39, on 20 June but it was postponed because of coronavirus.
“It’s official: Pulev vs. Joshua on 12 December in London,” Pulev posted on his official website on Monday.
“There is no way back, no postponement, no rescheduling! Let the better one win!” he added on Facebook.
Joshua, 30, beat Andy Ruiz to regain the WBA, IBF, WBO and IBO heavyweight titles in Saudi Arabia in December.
Pulev, the IBF’s mandatory challenger, said both fighters have signed their contracts for the fight.
Pulev has been waiting for a chance to face Joshua for almost three years after a shoulder injury forced him out of their planned world title bout in October 2017.
It is not clear if the fight will be behind closed doors because of Covid-19 restrictions.