Tyson Fury was "badly injured" in the run-up to his trilogy fight with Deontay Wilder, according to the heavyweight's father.
John Fury revealed his son needed injections in both elbows before beating the American for a second time and has since undergone surgery.
Fury was twice floored in the fourth round before fighting back to land an 11th-round knockout victory to retain his WBC title and unbeaten record in Las Vegas last month.
"Tyson was very badly injured going into that fight," John Fury told BT Sport.
"He was handicapped from the beginning. It wasn't a boxing match was it?
"He had to have cortisone injections into both elbows. He's since had an operation, six hours, all day in hospital having them sorted out. He had some bone spurs he had to get removed.
"He said to me afterwards 'I couldn't box, I couldn't work the jab. If I'd missed the jab it would've put me in limp mode and I wouldn't have been able to fight.
"'The pain when throwing the jab was unbearable so I was fighting two people - the pain in my own body and him. All we could do was make it a war and I wanted to win more than he did'."
