Anthony Joshua called Tyson Fury "a fraud" in a furious social media exchange after the news that their heavyweight showdown might be off.
The pair looked set for a highly-anticipated meeting in August, but an arbitration hearing ruled Fury must first face American Deontay Wilder.
In response, Fury challenged Joshua to a bare-knuckle fight.
The teams behind the two British heavyweights have engaged in lengthy negotiations to get what has been billed as one of the biggest fights in heavyweight boxing for decades over the line.
Joshua's promoter Eddie Hearn was adamant their fight was agreed - and on Sunday, Fury told his Instagram followers he too has signed off on a 14 August bout in Saudi Arabia.
Just 24 hours later, Wilder's team - who had always said he had a contract in place for a third Fury fight - found out their arbitration hearing was successful.
