A key part of "Pretty Woman" turned out to be improvised, according to the film's star, Richard Gere.

On Sunday, while attending a Cartier masterclass event at the Venice Film Festival, Gere revealed that a "sexy" scene between him and his co-star, Julia Roberts, was actually not meant to be a part of the movie.

"This was never in the script," Gere told the audience of a moment where Roberts' character, Vivan Ward, finds Gere's Edward Lewis in the Regent Beverly Wilshire Hotel, playing the piano. 

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Richard Gere looks surprised as Julia Roberts in a short blonde bob smiles in character in "Pretty Woman"

Richard Gere and Julia Roberts starred in the 1990 film, "Pretty Woman." (Touchstone/Kobal/Shutterstock)

What follows is a passionate, intimate moment shared between Gere and Roberts, who lies atop the piano. 

"We didn’t know how we would use it later. It ended up being integral to the film," he said, according to Variety.

"No chemistry," Gere joked of the scene, which was one of several of his own that played for the actor. "I mean, this actor and this actress, obviously, had no chemistry between them. . . . I haven’t seen that in a long time, too. It was a sexy, sexy scene."

Richard Gere in a dark grey suit soft smiles next to Julia Roberts in a white shirt and blue skirt in character during "Pretty Woman"

Richard Gere says he improvised the piano scene with Julia Roberts. (Moviestore/Shutterstock)

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In the movie, the now 75-year-old actor plays an affluent businessman who falls in love with a prostitute (Roberts), whom he hires to accompany him to events. Of the role, Gere said he played "a character who was almost criminally underwritten. It was basically a suit and a good haircut." 

Gere also acknowledged that the piano scene allowed Vivian "to see [Edward] in a complete different way. There was a mysterious yearning and maybe a damaged quality to this guy that she didn’t know."

He admitted a conversation with the film's director, Garry Marshall, was the inspiration behind it.

Richard Gere in a light blue shirt and black suit smiles as he sits on stage

Richard Gere smiles at an event during the Venice Film Festival on September 1. (Daniele Venturelli/WireImage/Getty Images)

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"Garry said to me, ‘What do you do at late at night in a hotel?'" Gere recalled, according to The Hollywood Reporter. "And I said, ‘Well, I’m usually jet-lagged, [that] would be the time I’m in a hotel. So I’m up all night and usually there’s a ballroom somewhere or a bar, and I’ll find a piano, and I’ll play the piano.’ He said: ‘Well, let’s do something with that. So we just basically improvised this scene, and he said, ‘Play something moody.’ I just started playing something moody that was this character’s interior life."

Garry Marshall in a black suit and purple tie laughs with Julia Roberts and Richard Gere, also in black on "TODAY"

The late Garry Marshall is photographed with Julia Roberts and Richard Gere in 2015. (Peter Kramer/NBC/NBC Newswire/NBCUniversal via Getty Images)

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This isn't the first scene that was reportedly improvised during the 1990 film. In an interview with the American Film Institute, Marshall, who died in 2016, revealed that the scene where Gere presents Roberts with a necklace was also organic.

"Some of the bits in ‘Pretty Woman,’ maybe people know, [were all] improvs and pranks for the gag reel," he explained. "I shot a piece – it ended up in the movie, where [Roberts] was dozing off a little bit 'cause she's 21-years-old . . . we do a jewelry scene where she gets a beautiful [necklace]. I said, ‘Richard, hit her with the box! Bang the box on her finger.' And [Roberts] laughed so honestly that we left it in the picture."