Muhammad Ali (left) battles Joe Frazier as referee Arthur Mercante watches, at Madison Square Garden in New York City, March 8, 1971. Neil Leifer/Sports Illustrated/Getty Images

Muhammad Ali became the world’s most famous athlete in large part because of his impact outside of the ring, but he never would have gained such adulation if not for his prowess in between the ropes. Ali ended his career with a 56-5 record as a pro, taking part in some of the most memorable bouts in the history of boxing.

Ali was a part of so many big fights that it’s difficult to compile a list of his best bouts. The first fight between Ali (then Cassius Clay) and Sonny Liston was the best fight of 1964, though their rematch a year later became one of the most controversial fights in history. Ali’s fights against the likes of Floyd Patterson and Leon Spinks rank high on the list, as well.

Below is a look at the five best fights of Ali’s storied career.

Muhammad Ali vs. Joe Frazier 1 (March 8, 1971)

Ali and Frazier had three classic fights that spanned nearly five years, but their first bout was easily the biggest. It was billed as “The Fight of the Century,” and the name holds up 45 years later. Both men entered the ring without a loss on their resume, and they were each guaranteed $2.5 million, which was a record at the time for any athlete. Frazier got the better of the man who would become his chief rival, knocking him down in the 15th round for the exclamation point on his unanimous decision victory.

muhammad ali
Muhammad Ali is widely recognized as the greatest boxer of all time. Getty Images

Muhammad Ali vs. Ken Norton (March 31, 1973)

Norton shocked much of the boxing world by upsetting Ali and becoming the new heavyweight champion. He would lose a rematch to Ali six months later, but Norton earned his place in history with a split decision over the greatest athlete to ever lace up a pair of gloves. Norton broke Ali’s jaw early on in the fight, and his victory was so surprising that it left some experts believing Ali could no longer fight at an elite level.

Muhammad Ali vs. Joe Frazier 2 (Jan. 28, 1974)

It had the least fanfare of the fights in the Ali-Frazier trilogy, but it remains one of the most important bouts of Ali’s career. Three years after dropping his heavyweight title to Frazier, Ali got his revenge in a non-championship fight. It lasted a full 12 rounds, and Ali came away with a narrow unanimous decision, winning no more than seven rounds on any of the judges’ scorecards.

Muhammad Ali vs. George Foreman (Oct. 30, 1974)

Ali earned a title shot against Foreman with his win over Frazier, setting up a fight that would go down as one of the most memorable boxing matches in history. “The Rumble in the Jungle” in Africa pitted the much-accomplished Ali against the younger Foreman, who entered the ring as a 4-1 favorite. But Ali proved that he was still the best heavyweight in the world, knocking Foreman out toward the end of the eighth round. Before ending the fight, Ali employed the now famous “Rope a Dope” strategy, withstanding punishment from Foreman for seven rounds.

Muhammad Ali vs. Joe Frazier 3 (Oct. 1, 1975)

The third and final fight between Ali and Frazier was the most brutal. It was the only one that didn’t go the distance, as Frazier's trainer Eddie Futch called for the fight to be over as his boxer slumped in the corner before the start of the 15th round. Ali kept his heavyweight belts, exhausted by the time of the final bell, leaving visible damage on his opponent’s face after the "Thrilla in Manilla."