Dereck Chisora has hailed Joe Frazier as "a real inspiration" following reports that the former world heavyweight champion is suffering from liver cancer.
Frazier, who was the first man to beat Muhammad Ali, is reported to be receiving hospice care in America.
British heavyweight Chisora said: "It's a sad time. I watched all the fighters as a kid and he was a real inspiration.
"I don't know him as a man but what he did for the sport in terms of entertainment - him and Muhammad Ali - was incredible.
"The guy's lived his life and you know what, if you have to die after you've achieved all you've achieved, you go in a good way.
"But it will be a sad day. What can you say about 'Smoking Joe'? A great fighter."
Frazier beat Ali on points in the so-called 'Fight of the Century' in 1971, but lost two further fights to Ali, including the epic 'Thrilla in Manila' in 1975.
Leading British promoter Frank Warren added: "I was very sad to hear the news, it's a tragedy.
"He's one of the greatest fighters of his generation and one of the best heavyweights in history. It's a sad thing and I know everyone in boxing will be wishing him well.
"He beat Ali once and was part of a great era, probably the best heavyweight era."