50 years ago today, 22-year-old challenger Cassius Clay (Muhammad Ali) battered the heavily favored heavyweight champion Sonny Liston in a bout that shook the boxing world. The fight ignited the career of one of sports’ most charismatic and controversial figures, whose bouts often became social and political events rather than simply sports contests. (Neil Leifer/SI)
GALLERY: Muhammad Ali vs. Sonny Liston I
GALLERY: SI’s 100 Greatest Photos of Muhammad Ali

50 years ago today, 22-year-old challenger Cassius Clay (Muhammad Ali) battered the heavily favored heavyweight champion Sonny Liston in a bout that shook the boxing world. The fight ignited the career of one of sports’ most charismatic and controversial figures, whose bouts often became social and political events rather than simply sports contests. (Neil Leifer/SI)

GALLERY: Muhammad Ali vs. Sonny Liston I

GALLERY: SI’s 100 Greatest Photos of Muhammad Ali

Muhammad Ali punches Ken Norton during their 1976 fight at Yankee Stadium. The two fought twice in 1973, splitting the fights, before the ‘76 rubber match. Ali slugged his way to a unanimous decision in 15 rounds. Norton’s own coaches believed their fighter had a comfortable lead heading into the 15th and advised Norton to stay away from Ali, which he did, possibly giving the fight away. After the bout, even Ali admitted he thought he had been beaten. (Jerry Cooke/SI)
GALLERY: The Best of Muhammad Ali

Muhammad Ali punches Ken Norton during their 1976 fight at Yankee Stadium. The two fought twice in 1973, splitting the fights, before the ‘76 rubber match. Ali slugged his way to a unanimous decision in 15 rounds. Norton’s own coaches believed their fighter had a comfortable lead heading into the 15th and advised Norton to stay away from Ali, which he did, possibly giving the fight away. After the bout, even Ali admitted he thought he had been beaten. (Jerry Cooke/SI)

GALLERY: The Best of Muhammad Ali

Today marks the 37-year anniversary of The Thrilla in Manilla, the historic rubber match between Muhammad Ali and Joe Frazier. The fight, which took place at the 16,500-seat Araneta Coliseum in Quezon City, was won by Ali via 14th round TKO. As this photo shows, Frazier’s left eye was swollen shut and left him unable to defend himself, forcing trainer Eddie Futch to throw in the towel before the final round. (Neil Leifer/SI)
GALLERY: Ali-Frazier III - The Thrilla in Manilla

Today marks the 37-year anniversary of The Thrilla in Manilla, the historic rubber match between Muhammad Ali and Joe Frazier. The fight, which took place at the 16,500-seat Araneta Coliseum in Quezon City, was won by Ali via 14th round TKO. As this photo shows, Frazier’s left eye was swollen shut and left him unable to defend himself, forcing trainer Eddie Futch to throw in the towel before the final round. (Neil Leifer/SI)

GALLERY: Ali-Frazier III - The Thrilla in Manilla