Diane Keaton and Jack Nicholson may both have a lifetime achievement award from the American Film Institute, but Keaton can still out-act Nicholson. At least, that was the case when the pair reunited for 2003's Something's Gotta Give, in which Keaton plays Nicholson's unexpected love interest. In the film, Keaton's acting was so convincing, Nicholson actually walked away from one scene in which she says "I love you" thinking she meant her lines.

“We’re rehearsing that scene in the street, where he’s running after her, and he calls me over after one rehearsal. He’s all rattled,” the writer and director Nancy Meyers said at Tribeca Film Festival, as Vulture notes. “I said, ‘What’s up?’ And he goes, ‘Diane just told me she loves me.’ I couldn’t tell if he was horrified or thrilled. So I was like, ‘Yes, I know, I wrote that line. It’s in the script, Jack.’ And he said, ‘Oh, okay.’ He thought she meant it. It’s really funny. That’s her.”

That's not to say Nicholson didn't get carried away himself during filming. He was particularly heartbroken after one scene, in which he serenades Keaton with "La Vie en Rose," didn't make the final cut. Meyers joked about it on Instagram recently, posting the clip with the caption, "#tbt to a deleted scene from SomethingsGottaGive. They were so great! Why did I ever delete this? Well, you can see it now. #JackAndDiane. Play with ?!"

Meyers also previously talked about how upset Nicholson was when he learned the scene wouldn't be included in the film. "He gets up to sing for her [Keaton's character], and it's 'La Vie En Rose,' which he sings to her in French. He worked really hard on it," she told WENN in 2012. "I had to cut the scene out because it just didn't fit the following scene, where he goes out with another woman. When it came time to tell Jack I was cutting out the scene, he didn't hold back his disappointment. He said, 'Chief, what do you mean?' He brings it up to me every time I see him, and recently I saw him for his birthday and he cornered me [and said], 'Now, about that scene...' To make it up to him, I put it in the DVD, so at least he can watch it on there."

Ironically, it was Keaton during filming who was worried about living up to Nicholson's acting abilities. "I mean, I hadn't seen Jack, besides passing him, like, twice in 25 years," she told Venice magazine. "So I didn't know what he would be like. Because in that span of time, you know, Jack became larger than legendary. He became a national treasure, which has not exactly happened to me. You know, I would see him on television peripherally at a Lakers game or read about him on the cover of Time magazine or see him at an awards show. I didn't know who he was."

Nicholson isn't completely off in thinking his former fling actually fell for him during filming, though. Keaton did enjoy their more intimate scenes. "In between takes, we were continually worried about how many kisses were we actually going to have to perform in front of everyone," she added. "But it was heaven to perform. Once the camera goes, you can just let those inhibitions go and you just enjoy it. I had a fabulous time." Jennifer Lawrence is so jealous right now.

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