In the dawn of their Hollywood careers, future Rocky star Sylvester Stallone and the eventual American Gigolo and Pretty Woman star Richard Gere were paired together for the 1974 film The Lords of Flatbush.

But when the film hit theaters, Gere was nowhere to be seen — Perry King had taken over the role Chico because of tension between the two actors. “We never hit it off,” Stallone told Ain’t It Cool News in 2006. “He would strut around in his oversized motorcycle jacket like he was the baddest knight at the round table.”

While both became bona fide leading men in their own rights, their rivalry has endured four decades — often thought to be the source of an unbelievable rumor about Gere and an unfortunate intimate incident with a gerbil (which even received a mention on Saturday Night Live), but also revealed to be the reason for a thwarted fistfight over Princess Diana, according to Elton John.

READ MORE: Inside Princess Diana and Elton John's Tight — but Often Complicated — Friendship

Stallone pushed Gere out of a car during an on-set lunch

From the start of their time together on the set of The Lords of Flatbush — a drama about Brooklyn street teens also starring Henry Winkler — tensions rose high between Stallone and Gere. “One day, during an improv, he grabbed me and got a little carried away,” Stallone said in the interview about the two simulating a fight scene. “I told him in a gentle fashion to lighten up, but he was completely in character and impossible to deal with.”

But the incident that really pushed Stallone over the edge happened in the back of a Toyota on a cold day in Coney Island. Stallone said that he was eating a hot dog when Gere entered with mustard-covered chicken that was sure to drip.

“He proceeds to bite into the chicken and a small, greasy river of mustard lands on my thigh,” Stallone explained. “I elbowed him in the side of the head and basically pushed him out of the car.”

Though they were on their lunch break, word about the incident quickly got out — and eventually Gere was fired. “To this day, [he] seriously dislikes me,” Stallone said in 2006. “He even thinks I’m the individual responsible for the gerbil rumor. Not true, but that’s the rumor.”

The ridiculous urban legend has gone so far that even Gere has addressed it. “I stopped reading the press a long time ago,” Gere told Metro UK in 2008. “There is an infamous ‘Gere stuck a hamster up his bum’ urban myth. I expect that sort of thing, but when reputable magazines started making up stories claiming I was in a country I had never been to with someone I didn’t even know, I just decided not to pay attention to any of it. It’s a waste of energy.”

Princess Diana chats with Sylvester Stallone at the Champion Children Awards held at London's Dorchester Hotel.

Princess Diana chats with Sylvester Stallone at the Champion Children Awards held at London's Dorchester Hotel in November 1993

According to John, Gere and Stallone almost got into a fistfight over Diana

A decade later, when John released his autobiography Me in 2019, one story jumped out — after all, it included two Hollywood heavyweights and a British royal.

John wrote about a dinner party he hosted with high-powered guests including Jeffrey Katzenberg, George Michael, Richard Curtis and Emma Freud, as well as Gere and Stallone.

“The most peculiar scene developed,” John wrote in his book. “Straight away, Richard Gere and Diana seemed very taken with each other.”

John remembers Gere and Diana deep in conversation in front of the fireplace when the mood of the party changed: “As the rest of us chatted, I couldn't help notice a strange atmosphere in the room. Judging by the kind of looks he kept shooting them, Diana and Richard Gere's newly blossoming friendship was not going down well with Sylvester Stallone at all. I think he may have turned up to the party with the express intention of picking Diana up, only to find his plans for the evening ruined.”

When it was time to eat, the group moved over to the dining room, but Gere and Stallone were noticeably missing, according to the book. So John sent his partner David Furnish to find them.

“He came back with both of them, but he was wearing a fairly ashen expression,” John wrote, saying that Furnish relayed that there was “a situation.”

According to John, “It transpired that he'd discovered Sylvester Stallone and Richard Gere in the corridor, squaring up to each other, apparently about to settle their differences over Diana by having a fistfight.”

Furnish had broken it up just in time by calling them to dinner.

After the awkward meal, Diana and Gere went back to the fireplace and Stallone “stormed off home.”

“I never would have come if I'd known Prince f****n' Charming was gonna be here.,” Stallone snapped, according to John. “If I'd wanted her, I would've taken her!”

Richard Gere

Richard Gere, 1990

John laughed off the incident

Despite the potential seriousness of the mounting tension, as soon as Stallone was out of the picture, the mood lightened.

“We managed to wait until his car was out of sight before we started laughing,” John wrote. “Back in our living room, Diana and Richard Gere were still gazing raptly at each other. She seemed completely unruffled.”

While only those inside the party know the exact course of events from that night, John stands by his story, while, in response to fan asking about the incident, Stallone buried in the comments of an old Instagram post “Complete fabrication.”

Whatever did or didn’t happen over the royal inside John’s home, Stallone and Gere have never starred in a movie together — or even appeared at an event together — in the four decades they’ve both been working in Hollywood.