Joe Frazier, who has died at the age of 67, today received tributes from the two men who helped him define the greatest era of heavyweight boxing.
It emerged over the weekend that Frazier, the former undisputed world heavyweight champion, was fighting liver cancer and he was reported to be in hospice care.
His family confirmed he had passed away in a statement reported by Philadelphia's WPVI-TV this morning, which read: "We, the family of the 1964 Olympic boxing heavyweight gold-medallist, former heavyweight boxing champion and International Boxing Hall of Fame member Smokin' Joe Frazier, regret to inform you of his passing.
"He transitioned from this life as "One of God's Men", on the eve of November 7, 2011 at his home in Philadelphia, Pennsylvania. We thank you for your prayers for our father and vast outpouring of love and support."
Frazier won Olympic gold in 1964 after going to the Games as a replacement for the injured Buster Mathis, who had beaten him in the trials.
He also won the professional heavyweight title in 1970 by stopping Jimmy Ellis in the fifth round at Madison Square Garden and defended it successfully four times.
He is best remembered for his fights with fellow boxing legends Muhammad Ali and George Foreman.
Frazier beat Ali on points in the so-called 'Fight of the Century' in 1971, but lost in two further meetings including the epic 'Thrilla in Manila' in 1975.
He fought Foreman twice, losing by technical knockout in both 1973 and 1976.
In what is the most storied era in the sport's history, it was Ali, Foreman and Frazier who were its pre-eminent stars.
Today Ali said: "The world has lost a great champion. I will always remember Joe with respect and admiration.
"My sympathy goes out to his family and loved ones."
The pair had an at-times fraught relationship, dating back to taunts Ali directed at his rival in the build-up to their famous trilogy of fights.
But they were reported to have been on better terms in recent years.
Foreman tweeted his reaction to the news, saying: "Good night Joe Frazier. I love you dear friend."
Frazier retired in 1976 after losing a rematch against Foreman, and aborted an attempted comeback five years later after a draw with the unheralded Jumbo Cummings.
Joe Bugner, another star of the heavyweight division in the 1970s, lost to Frazier five months after being beaten by Ali in 1973.
But it was the fight against Frazier, who visited Bugner in Australia for his 60th birthday last year, which the Hungary-born fighter felt was a turning point in his career.
"Joe Frazier was relentless," Bugner told BBC Radio 5 Live. "Here was a man about 5ft 10, he weighed about a stone lighter than myself, but he was so courageous and ferocious, you had to literally hit him with a sledgehammer to put him away.
"In 1973 I was 23 years old. I became a man after that fight because I realised you can't go through a career like boxing without seeing and feeling the power of the greats.
"I happened to have the privilege of fighting Joe Frazier and Muhammad Ali and a few others but those two to me were the greatest.
"Joe took everything away I thought I had and made me realise I needed more, if I was going to succeed I needed a lot more.
"I'm so proud I fought him and I'm so proud he came to my birthday last year.
"It hit me like a lightning bolt when I heard he died."
British former heavyweight champion Lennox Lewis added on 5 Live: "He definitely was legendary and he made a great contribution to boxing.
"I'm so sad for his family. Nobody likes to hear about great heroes passing on. It's very sad for boxing today."
Vitali Klitschko, WBC champion and brother of fellow heavyweight Wladimir, said Frazier's legacy resonated down the generations.
"He was a huge fighter, huge champion, huge personality," Klitschko, 40, told BBC Radio 5 Live. "We had a chance to see the fights. It was a great lesson for all new generations."
More stars of the sport took to Twitter to share their thoughts, with Floyd Mayweather writing: "RIP Smokin Joe. My thoughts and prayers go out to to the Frazier family. We lost an all time great tonight."
Oscar De La Hoya wrote simply: "I will miss you my friend. R.I.P. Joe frazier", while Shane Mosley added: "Joe Frazier one of the greatest heavy weight champion ever. RIP."
Promoter Frank Warren believes his fights with Ali and Foreman mean Frazier will be remembered as one of the sport's greats.
Warren told 5 Live: "He was part of that era of the best heavyweights there have ever been.
"The trilogy of fights that he had with Muhammad Ali, the tough fight he had with George Foreman and the good wins on the way - he was one of the most exciting heavyweights ever."