Frazier, 67, was the first man to defeat the legendary Ali, taking the undisputed heavyweight title with a unanimous 15-round decision over Ali in 1971 at Madison Square Garden in what was dubbed the “Fight of the Century”.
Ali won a unanimous 12-round decision in a 1974 rematch and famously completed the trilogy with a victory in 1975 at the “Thrilla in Manila” by stopping Frazier after 14 rounds in their epic slugfest in the Philippines.
A year later “Smokin’ Joe” lost for the fourth and final time in his career when George Foreman knocked him down twice before the fight was stopped in fifth round.
Frazier’s illness was first reported by the New York Post, citing an unidentified source.
Frazier began his career with 29 consecutive wins, taking the heavyweight title in 1970 by stopping Jimmy Ellis in the fifth round of their fight at Madison Square Garden.
He defended the title four times before running into the bigger and stronger Foreman in 1973, suffering his first defeat and losing the heavyweight crown when he was knocked down six times in two rounds in Kingston, Jamaica.
Frazier retired following the second Foreman fight in 1976 but returned for one more bout in 1981 at age 37.
In recent years, Frazier turned to singing forming a back-up group called the Knockouts.