Angelo Dundee and boxer Cassius Clay (later Muhammad Ali), during a training session in 1966. George Freston/Fox Photos/Hulton Archive/Getty Images hide caption

itoggle caption George Freston/Fox Photos/Hulton Archive/Getty Images

Joe Frazier (left) hits Muhammad Ali during the 15th round of their heavyweight title bout — the "Fight of the Century" — at New York's Madison Square Garden in March 1971. AP hide caption

itoggle caption AP