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Kevin O’Leary reflected on one of the most memorable — and definitely the most brutal — scene in the Oscar-nominated "Marty Supreme" in which his character paddles Timothée Chalamet to humiliate him.

The "Shark Tank" star told Fox News Digital that they started shooting the scene around 3:45 in the morning, and a stunt performer was going to take the beating, not the A-list Chalamet.

"We had a stunt a--," O’Leary explained. "And the idea was the stunt a-- would come in. We had a fake paddle with a silicon hinge on it, and that broke on the first hit. It just didn't work. It didn't even look real."

Then he said Chalamet surprised everyone by proclaiming: "‘Wait a second, it's gonna be my a--. I'm not gonna let someone else immortalize their a-- as my a--, I'll do my a--!’ And I said, ‘Look, man, we're gonna go to a real paddle here. I'll try and hold back.’"

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Kevin O'Leary with Timothee Chalamet in Marty Supreme

Kevin O'Leary with Timothée Chalamet in "Marty Supreme." (Zoey Kang/A24)

But when he did some slower hits, the director, Josh Safdie, said it wasn’t working and didn’t look real.

"‘This is a crucial scene in the discipline, and we need the real thing,’" Safdie explained, according to O’Leary. "'So, Timmy, either let the, you know, stunt a-- sit in, or you're gonna get your a-- whacked.’"

WATCH: KEVIN O'LEARY ON BRUTAL ‘MARTY SUPREME’ SCENE THAT EVEN FILM CREW STRUGGLED TO WATCH

The first-time feature film actor said he "laid into him, and he got his a-- whacks one cheek at a time, so the other could cool down. You know, but I imprinted the brand of that paddle in his left cheek."

Filming the scene was so intense, O’Leary said some of the crew said they needed to step away.

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"It's now 4.30 in the morning. It was insane, you know, like, it was just nuts," he told Fox News Digital. "The whole thing was crazy, and we were doing it, and we weren't following the script, and it ended up being a very important scene in the movie, and it pulled a lot out of us because even some of the extras and even some the camera guys and lighting guys said afterwards: ‘This is really hard to watch. And we need to take a few seconds off. Like, let's just take a couple of seconds between these takes.’"

Timothee Chalamet playing ping pong in "Marty Supreme"

Timothée Chalamet playing ping pong in a scene from "Marty Supreme." (Zoey Kang/A24)

O’Leary estimated it took 30 to 40 takes to get through the scene.

But he said he knew right away that Chalamet would win an Oscar.

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The 30-year-old received an Academy Award nomination for best actor on Jan. 22.

"When we shot in Tokyo, I said to Safdie, third day in Tokyo: ‘Academy Award, man,’ and I'm going to be right because I was across from him doing all that vampire stuff, and he was putting out some really unreal energy, and it shows in every frame that he's a little freaked out and, you know, that whole thing just, that's when I knew. This kid is incredible, and he's going to win an Oscar, and he is going to win an Oscar."

Kevin Oleary on Shark Tank

Kevin O'Leary on the set of "Shark Tank." (Christopher Willard/Disney via Getty Images)

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O’Leary explained that the film was shot "old school" in 35 mm.

"I've been doing TV for 20 years plus, but there's something magic about film that you just don't get in television," the businessman and reality show veteran said.

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He added that the "chaos" of being on a film set differed greatly from the organized world of business.

"It's a very interesting change from the binary world I live in of finance and business investment and real estate and everything else," he admitted. "This is just, it's just sheer chaos. It's just total chaos. And you know, the creative aspect is often improvised … Some of the best lines in that movie were on the 20th take. There were mistakes, and that's how it was formed. And then, of course, the genius of cutting it and editing it and the way those guys worked together. Safdie and [co-producer and writer] Ronald Bronstein, I mean, it was a remarkable outcome."