Sugar Ray Robinson, the greatest fighter of all time, might’ve thrown his greatest punch on this date 63 years ago at Chicago Stadium.

Robinson would turn 36 two days after May 1, 1957, meaning he was well past his prime when he climbed through the ropes to face middleweight champ Gene Fullmer in a rematch of their first fight four months earlier. Fullmer, a future Hall of Famer in his prime, had won a unanimous decision.

And, following a familiar pattern, Fullmer was ahead after four rounds of the second fight. Then, in the fifth, he made a historic mistake. He stepped toward Robinson with his right hand too low and BAM!

The punch that became known as the “perfect left hook” landed on Fullmer’s chin and put him on his back. He rolled to his side and attempted to get up but couldn’t do so. The fight was over, although it took a while for Fullmer to realize it.

“It supposedly was the greatest left hook he ever threw and it happened to hit me on the chin,” Fullmer said years later, beginning a story he was tell many times. “When I came to, I was standing up and he was standing in the other corner jumping up and down.

“I asked my manager, I said, ‘How come Robinson is doing exercises between rounds?’ He said, ‘It’s not between rounds.’ I said, ‘What do you mean?’ He said, ‘They counted 10.’ I said, ‘It must’ve been me because I never heard any of it.”

Robinson’s reign – his fourth as 160-pound champion and fifth overall – didn’t last long. He lost his belt by split decision to another rival, Carmen Basilio, four months later but would fight another eight years, mostly at a high level.

He regained the middleweight title one more time when he turned the tables on Basilio in March 1958 before losing it to Paul Pender in January 1960. He would never win another championship but his legacy had been etched in stone many years earlier. Robinson was the best.

And don’t feel badly for Fullmer. “Cyclone” would fight Robinson two more times, drawing in 1960 and winning on points the following year. He was a two-time middleweight titleholder and one of the better fighters of his era.

And, of course, his chin played a key role in one of the sport’s most memorable moments.