On March 24, 1975, an underdog fighter, Chuck Wepner, “The Bayonne Bleeder” challenged Heavyweight Champion Muhammad Ali for the title. A world-ranked contender, Wepner trained for eight weeks in advance of the boxing match held in Ohio.

A then unknown writer and aspiring young actor attended the fight, too.

In an excerpt from Sylvester Stallone’s “The Rocky Scrapbook“, Sly explains that night in 1975:

“Through fate or whatever, I ended up at the Muhammad Ali-Chuck Wepner fight. Wepner, a battling bruising type of club fighter who had never really made the big, big time, was now having his shot. But the fight was not regarded as a serious battle. It was called a public joke. He would barely go three rounds, most of the predictions said.

Well, the history books will read that he went 15 rounds and established himself as one of the few men who had ever gone the distance with Muhammad Ali, and he can hold his head up high forever no matter what happens.”

In the 9th round of the fight, Muhammad Ali was knocked down. Various reports attribute it to a powerful wallop from Wepner, a slip on the canvas, or that Wepner stepped on Ali’s toes – a fact actually confirmed by photos of that moment. In any case, the idea of an unknown challenger knocking down the Heavyweight Champ – and the greatest in the world, no less – instantly sparked in Sylvester Stallone’s creative mind.

“That night I went home and I had the beginning of my character. I had him now. I was going to make a creation called Rocky Balboa, a man from the streets, a walking cliché of sorts, the all-American tragedy, a man who didn’t have much mentality but had incredible emotion and patriotism and spirituality and good nature even though nature had not been good to him. All he required from life was a warm bed and some food and maybe a laugh during the day. He was a man of simple tastes.” (Official Rocky Scrapbook)

Screenwriter Stallone used the legendary Ali as the basis for his character of Apollo Creed, beautifully personified by Carl Weathers in four of the seven films in the series. What character traits that are shared between Chuck Wepner and Rocky Balboa are very debatable beyond the fact that they both went the distance with the greatest fighter in the world. Check out the video above for the fight footage filmed that night, along with audio commentary from Chuck Wepner himself.

In 2003, Wepner sued Sylvester Stallone for using his “life story” as the basis of Rocky; the case was quietly settled between the two men for an undisclosed amount. (Read more about the settlement.)