Nicole Kidman & Javier Bardem on Toughest Part of Lucille Ball and Desi Arnaz Transformations (Exclusive)

The 'Being the Ricardo' stars chatted with ET about becoming the iconic couple and comedy legends.

Nicole Kidman and Javier Bardem were fully prepared to become Lucille Ball and Desi Arnaz.

The actors take on the role of the iconic couple and comedy legends in Being the Ricardos. ET's Nischelle Turner spoke with Oscar winners at the New York Premiere at Jazz at Lincoln Center on Thursday, where they shared the toughest part of transforming into Ball and Arnaz.

"I think that demystifying [her], that's where I was lucky that [director] Aaron Sorkin felt so confident in what he'd written, and what he was doing was the story he wanted to tell," Kidman expressed. "That's the great thing about being an actor, is you actually are in the hands of the director. We're not the person controlling or steering it, so if he wants it, that was what he wants. That was what he stated from the very beginning, 'I want you to humanize her. Make them real.'"

As for Bardem, the thing that struck him the most about the Cuban performer was "his energy, his ability to be not only the great comedian that he was, but also the protector of the show and the protector of her as a man, as a husband, and also as a partner."

"And he was on [at] the same time, being the producer of the show, musician, singer, dancer. He was so many things at the same time," he continued. "But he was very relaxed with everything, he was a very kind, loving, caring, fun man to be with. And he didn't feel the pressure on his shoulders, that's a lot."

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Being the Ricardos follows the famous pair during one critical production week of their sitcom, I Love Lucy, which comes at a time when they're being threatened by shocking personal accusations, a political smear, and cultural taboos.

Kidman shared that filming the iconic I Love Lucy grape scene was her favorite, expressing, "Being able to play a woman who was so extraordinary in what she accomplished and what she [did], her talent, [that was my favorite]."

"Also just in her resilience and her ability to not apologize for who she was. I think she got to this stage in her life where she was like, 'I'm smart, I'm good at what I do and I'm not gonna apologize for that,'" Kidman added. "Which is a really fascinating, direct, sort of way of behaving and she was like that. Not at the beginning, you know, but she became like that. But also then as a physical comedian she was just exquisite. And to get lost in that as an actor was absolutely new territory for me."

Kidman and Bardem were also thrilled to have had the couple's daughter Lucie Arnaz's stamp of approval.

"It means everything. It means absolutely everything," Bardem stated. "It means there's nothing that can top that. I mean, no review, no word, no recognition from anybody else but the family. And that's the obsession that I had -- and I guess Nicole, as well -- when I was playing the role. I was playing her father. But [when] the daughter says, 'Yes, you got it right,' it's everything."

Kidman added that is was a "huge relief" for her. "Probably the most important stamp of approval for us. I know for all of us in the film that was so important. And yeah, we're playing her parents right."

Being the Ricardos arrives in theaters Dec. 10 and streams Dec. 21 on Prime Video. See more in the video below.