Tyson Fury is moving closer to being stripped of his world heavyweight titles after the WBO gave him 10 days to clarify his medical status.
Fury was due to defend his WBA and WBO belts against Wladimir Klitschko on October 29, but the fight was called off for a second time after his management team declared he was "medically unfit to fight".
The undefeated 28-year-old, who withdrew from the original July 9 date due to an ankle injury, could now lose his titles which he won when he ended Klitschko's 11-year reign at the top in November last year.
Eddie Hearn believes Fury will to be stripped of his world titles and says talks have taken place for Anthony Joshua to step in to face Klitschko.
Fury was quickly stripped by the IBF title in the wake of the glorious victory over Klitschko in November 2015, leaving Joshua to seize that strap by annihilating Charles Martin in April.
The WBO sent a letter to Fury on Monday asking that his doctor contacts them to clarify the nature of his condition and gave him 10 days to respond.
The letter said: "We would appreciate that the physician specifically clarifies the nature and extent of your condition and your prognosis for return to training and your return to competition.
"If the Championship Committee does not receive the complete requested information, i.e. the Interim Certification, together with the Psychological and/or Mental Evaluation, within the allotted time frame of 10 days, the Committee will proceed with the necessary appropriate action without the benefit of an appeal."
WBA president Gilberto Mendoza also said his organisation are looking into the reason for Fury's withdrawal.
"I heard the news," Mendoza told Sky Sports. "I have not received anything official from Tyson Fury's camp.
"Let's see what happens. I think we're going to enquire with Tyson Fury to see what has happened."