The five fights that defined Muhammad Ali the boxer (in chronological order).

SONNY LISTON
Date: Feb. 25, 1964
Location: Miami Beach, Fla.
Ali’s record: 19-0 (15 KOs)
Liston’s record: 35-1 (29 KOs)
Result: KO 7
Background: Cassius Clay didn’t have a chance to beat then-heavyweight champion Sonny Liston, or so almost everyone believed at the time. The brash, but relatively inexperienced 22-year-old was an 8-1 underdog against his menacing opponent; 43 of 46 boxing writers polled picked Liston to win. Why bother? Well, the champ had never seen anything like Clay before. The gifted youngster baffled the “Ugly Bear” with his boxing skills, athleticism and stunning quickness, picking the helpless titleholder apart and frustrating him to a point where he simply gave up on his stool after the sixth round. “I shook up the world,” Clay famously yelled in the ring afterward. Indeed he did. Boxing would never be the same.

CLEVELAND WILLIAMS
Date: Nov. 14, 1966
Location: Houston
Ali’s record: 26-0 (21 KOs)
Williams’ record: 65-5-1 (51 KOs)
Result: KO 3
Background: Ali’s victory over Cleveland Williams was not as important as some other fights in his career. It just happened to be him at his best, according to many observers. He would fight only twice more before his government-imposed hiatus from boxing, meaning he was near the end of his first incarnation. The once-lanky Ali had filled out, had gained experience and was never quicker, which meant big trouble for Williams, who couldn’t see Ali’s punches coming let alone avoid them. The “Big Cat” didn’t last three rounds. According to CompuBox, which tallied punches from video, Ali landed 62 percent of his punches (46 of 74) while Williams connected only 10 times. “That night, he was the most devastating fighter who ever lived,” Howard Cosell told Thomas Hauser.

JOE FRAZIER I
Date: March 8, 1971
Location: New York
Ali’s record: 31-0 (25 KOs)
Frazier’s record: 26-0 (23 KOs)
Result: L UD 15
Background: “The Fight of the Century” was arguably the biggest event in boxing history, providing a grand stage for the undefeated fighters – both of whom had legitimate claims to the heavyweight title – at the famed Madison Square Garden. As colleague Doug Fischer put it, “The world stood still for that fight.” Ali got off to a quick start but couldn’t maintain his pace and ultimately took more punishing shots than the world was accustomed to seeing. Frazier capped his performance by putting his rival down with a historic left hook in the 15th round, ensuring his unanimous-decision victory. Ali was exposed as human after all but he was far from finished, as he would beat Frazier in the second and third fights of their trilogy and shock the world once more three-plus years later.

GEORGE FOREMAN
Date: Oct. 30, 1974
Location: Kinshasa, Zaire (now Congo)
Ali’s record: 44-2 (31 KOs)
Foreman’s record: 40-0 (37 KOs)
Result: KO 8
Background: It was Sonny Liston all over again. Then-champion George Foreman was unbeaten and seemingly invincible, having stopping all but three of his 40 opponents. Ali, now 32 and slower afoot, had beaten Joe Frazier in their second fight nine months earlier but the hulking Foreman was deemed to be a much bigger mountain to climb. Ali had a plan, though, which would become known as “rope-a-dope”: He would allow Foreman to punch himself out. That’s exactly what happened by the eighth and final round. It allowed Ali to do the impossible – not only win but knock out Foreman to become champion a second time. In the process, he sealed his fate as a fighter for the ages.

JOE FRAZIER III
Date: Oct. 1, 1975
Location: Manila, Philippines
Ali’s record: 48-2 (34 KOs)
Frazier’s record: 32-2 (27 KOs)
Result: KO 14
Background: Ali had nothing to prove by this point, although he certainly wanted to win the rubber match with his greatest rival, called the “Thrilla in Manila.” In the end, he not only won the fight but demonstrated beyond any doubt that his fighting spirit rivaled his remarkable abilities. This was the real fight of the century, as Ali and Frazier engaged in a savage give-and-take war of attrition that was arguably the best heavyweight scrap ever. Frazier was so badly beaten that his corner threw in the towel after the 14th round but Ali hadn’t escaped the fight’s ravages. “What you saw,” he said afterward, “was next to death.” Ali would fight 10 more times but the “Thrilla” was his last great performance.