As an amateur, Cassius Clay appeared in 108 bouts between 1955 and 1960. He won six Kentucky Golden Glove titles, two national Amateur Athletic Union (AAU) championships, two National Golden Glove crowns and the Gold Medal in the light heavyweight division in the 1960 Summer Olympic games in Rome, Italy. He was only 18 years old.

On February 25, 1964, in Miami Beach, Florida, Clay waged his first challenge for the heavyweight championship in a match against Sonny Liston. Though Liston was thought by many to be invincible, the brass 22-year-old Clay spent the weeks leading up to the fight entertaining reporters and fans with colorfully worded promises of his impending victory. In one of the most stunning upsets in boxing history, Clay delivered on his promise, knocking Liston out in the seventh round.

Clay won his next 29 fights, 23 by knockout.

After defeating Liston, Clay startled the nation by announcing that he had joined the Nation of Islam and had changed his name to Muhammad Ali. His affiliation with the Nation of Islam came at a time when many Americans and many of his fans considered the Black Muslims a subversive and dangerous organization.

In 1967, the Vietnam War was raging. The U.S. Government sent Ali a draft notice; citing his Islamic faith, Ali refused induction into the military. He was stripped of his heavyweight title and his boxing license was revoked. The government gave him a five-year jail sentence for defying military induction. At 27, in the peak of his career, the only opponent Ali was allowed to fight was the federal government.

With his bold assertions of black pride, Ali became a "Black Power" symbol. He was controversial, polarizing and nobody wanted to hire him. With mounting bills from his legal appeals and no income, he needed to make some money quickly.