The trilogy fight between Tyson Fury and Deontay Wilder in Las Vegas on 24 July has been postponed after the Briton tested positive for coronavirus.
A source close to Fury said the WBC world heavyweight champion was deeply frustrated by the situation.
Fury tested positive on Thursday and after discussions with medical experts the fight was called off – it is likely to be rescheduled for October.
Fury beat Wilder to become WBC champion in February 2020 – 14 months after the pair shared a thrilling draw in Los Angeles.
Neither man has fought since Fury’s victory in Las Vegas.
Fury is unbeaten in his 31 fights, while Wilder has just one defeat in 44 outings.