Boxers Muhammad Ali and Sonny Liston during match in which Ali retained his heavyweight title.

American Heavyweight boxer Cassius Clay (later Muhammad Ali) lying on his hotel bed in London. He holds up five fingers in a prediction of how many rounds it will take him to knock out British boxer Henry Cooper.

Heavyweight Boxing Champion of the World, Cassius Clay, who later changed his name to Muhammad Ali.

American heavyweight boxer Muhammad Ali (right) hits Floyd Patterson (1935 - 2006) during a bout at the Convention Center, Las Vegas, Nevada, November 22, 1965. Ali went on to win on the fight.

World heavyweight boxing champion Muhammad Ali in training at the Royal Artillery Gymnasium in London for his upcoming fight with British champion Henry Cooper, against whom he must defend his title.

Floyd Patterson and Muhammad Ali (aka Cassius Clay) each land a blow on the other. Ali won and retained his title of heavyweight champion.

Boxing champion Muhammad Ali posing in front of the Alvin Theater where the play 'The Great White Hope' was playing.

American heavyweight boxing champion Muhammad Ali walks through the streets with members of the Black Panther Party, New York, New York, September 1970. Ali was sentenced to five years in prison and his championship title revoked after...Meer

Closeup of Muhammad Ali in corner during fight vs Larry Holmes at Ceasars Palace. Cover. Las Vegas, NV 10/2/1980

Heavyweight champion Muhammad Ali lunges at challenger Joe Frazier during the 10th round of a boxing match in Manila in 1975. Ali won a 14th round TKO over Frazier.

Muhammad Ali during training for his fight with Al 'Blue' Lewis held in Dublin, Republic of Ireland in 1972.

George Foreman tries to get off the canvas as referee Zack Clayton checks on him during the match against Muhammad Ali at 20th of May Stadium. Kinshasa, Zaire

American boxer Muhammad Ali (born Cassius Clay) (right) lands a punch at Joe Frazier (1944 - 2011) during their bout in the ring at Araneta Coliseum, Quezon City, Philippines, October 1, 1975. Referee Carlos Padilla is visible in...Meer

World Heavyweight Champion boxer Muhammad Ali addressing a Nation of Islam meeting at the New Victoria Theatre in London.

Closeup portrait of Muhammad Ali during training, Deer Lake, PA 8/29/1978

Muhammad Ali punches a globe at the Plaza Hotel in Rome, Italy, 6th February 2001. The great career of the most famous American boxer is highlighted by an Olympic gold medal in light- heavyweight at the Rome 1960 Games and three World...Meer

Muhammad Ali onstage during the Michael J. Fox Foundation's 2010 Benefit 'A Funny Thing Happened on the Way to Cure Parkinson's' at The Waldorf=Astoria on November 13, 2010 in New York City.