How it unfolded
This was the first-ever matchup of two undefeated fighters for the heavyweight title. Ali, who had lost three and a half years to draft-refusal exile, returned 31-0; Frazier, who had become champion in the interim, was 26-0. Each fighter was guaranteed $2.5 million, an unprecedented sum at the time. Madison Square Garden was packed with celebrities, and Frank Sinatra shot photos ringside. Ali took the early rounds with speed, but Frazier bobbed side to side and pressed forward relentlessly, alternating left hooks to the body and head. From the middle rounds Ali spent more and more time leaning on the ropes. In the 11th, a Frazier hook badly shook Ali, and in the 15th a clean left hook decked him to the canvas. Ali rose and survived to the final bell, but all three judges gave the fight to Frazier. It was Ali's first professional loss.
Why it still matters
This was the first time the phrase 'Fight of the Century' was not an exaggeration. Watched by hundreds of millions worldwide via closed-circuit broadcast, it proved boxing could become a truly global media event, and it launched the two men's trilogy and the golden age of 1970s heavyweight boxing. Ali's second career began right where his unbeaten myth broke.