Returning from his forced suspension, Ali faced Joe Frazier on March 8, 1971, in what was billed as the "Fight of the Century", due to the tremendous excitement surrounding a bout between two undefeated fighters, each with a legitimate claim to be heavyweight champion. The fight lived up to its billing, but it was Smoking Joe's night, as he won by unanimous decision with scores of 11-4, 9-6, and 8-6.

In 1971, Los Angeles Laker Wilt Chamberlain challenged Ali to a fight, and a bout was scheduled for July 26. Although the seven-foot-two-inch Chamberlain had formidable physical advantages over Ali--weighing 60 pounds more and able to reach 14 inches further--he was unsettled by Ali's taunts of "Timber!" and "The tree will fall" during a shared interview. When Lakers owner Jack Kent Cooke offered him a record-setting contract, conditional on Chamberlain agreeing to abandon what Cooke termed "this boxing foolishness", he did exactly that.

In 1973, rising young contender Ken Norton broke Ali's jaw while handing him the second loss of his career. After initially considering retirement, Ali would instead make a comeback, winning a controversial decision against Norton in their second bout.

The Rumble in the Jungle has been called "arguably the greatest sporting event of the 20th century." It was a major upset victory for Ali who came in as a 4-1 underdog against the heavy-hitting Foreman. The fight is notable for Ali's use of the rope-a-dope tactic, letting Foreman land body blows in order to tire him.

In a fight that was billed as Give the White Guy a Break, 35-year-old Chuck Wepner, a journeyman known as "The Bayonne Bleeder", stunned Ali with a knockdown in the ninth round. While Ali would win by knockout in the 15th round, the fight inspired Stallone to create the character of Rocky Balboa. Like Wepner, Rocky lasts 15 rounds, but unlike Wepner, he actually "goes the distance".

The Thrilla in Manila is consistently ranked as one of the best and most brutal fights in boxing history and was the culmination of a three-bout rivalry between Ali and Joe Frazier. Ali won by technical knockout after Frazier's chief second, Eddie Futch, asked the referee to stop the fight following the end of the 14th round. The contest's name is derived from Ali's rhyming boast that the fight would be "a killa and a thrilla and a chilla, when I get that gorilla in Manila."

Ali used the "Accupunch" to knock out U.K. heavyweight champion Richard Dunn in 1975. It was taught to him by Taekwondo Grandmaster Jhoon Rhee, who learned it from legendary martial artist Bruce Lee. After Dunn went to the floor, Ali played to the crowd, comically windmilling for his next punch to encourage the referee to end the match.

Ali appeared on the cover of Sports Illustrated on 38 different occasions, second only to Michael Jordan's 46.

By the end of his career, Ali had absorbed an estimated 200,000 hits.

In 1963, Ali released an album of spoken word music on Columbia Records titled, I Am the Greatest, which reached number 61 on the album chart and was nominated for a Grammy Award. As a "rhyming trickster", he was noted for his "funky delivery, flow, and braggadocio." Based on this album, some have even argued that Ali was the first rapper.