Nicole Kidman Sings Cover of 'Dream a Little Dream of Me' for The Undoing Opening Titles

Nicole Kidman Sings Cover of 'Dream a Little Dream of Me' for The Undoing Opening Titles

"I can't do with my voice what I can do when I act, and that's very frustrating," Nicole Kidman has said about her singing abilities

It's no big or little lie — Nicole Kidman sings the theme song for her latest TV show!

On Sunday, The Undoing premiered on HBO, a new thriller limited series from the Big Little Lies star, 53, in which she stars opposite Hugh Grant as their ritzy Manhattan life slowly crumbles amid a scandalous murder mystery.

But before audiences got to meet Kidman's character Grace Fraser, they heard the actress' musical stylings as she performed a cover of "Dream a Little Dream of Me" for the opening title sequence.

Kidman's no stranger to singing, of course. The Oscar winner is known for her movie-musical role in 2001's Moulin Rouge, and she also appeared in 2009's Nine. Next, Kidman is set for Netflix's The Prom adaptation, debuting later this year. (Not to mention she's married to country music star Keith Urban!)

Earlier this month, however, Kidman told the Sydney Morning Herald that singing is not within her comfort zone.

"I can't do with my voice what I can do when I act, and that's very frustrating," she said. "With performance, there's the possibility I may not get there. But at least I know I can try to reach it. With voice, I just can't. I wish I could sing what I feel."

Niko Tavernise/HBO Nicole Kidman in The Undoing

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In a conversation for Marie Claire, Kidman and Grant, 60, opened up about their chemistry in sharing the screen for the first time together in The Undoing. Grant said his costar was "very good at making us connect" during the shoot.

"Yeah, well, I like you. So that was a really easy part," she said of their rapport. "I remember lying around on that bed when we were shooting in the bedroom, and talking to [director Susanne Bier] and thinking, 'Huh, this is the good part. I'm gonna miss this.'"

"Because there was something very relaxed, obviously, because I'm Australian and you're British, we have that similar, I don't know, it's just a sense of humor," added Kidman. "It's good chemistry."

RELATED: Nicole Kidman and Hugh Grant on How Their Friendship Helped Them Connect in HBO's The Undoing

In a recent joint interview with Entertainment Tonight, the pair said they were able to connect so well on-screen "because we've known each other since we were in our early 20s." The series also stars Donald Sutherland, Edgar Ramirez, Noah Jupe and Lily Rabe.

"I feel very comfortable with him, and part of what it took for this to work is that this couple has to be very sort of comfortable and happy," said Kidman, asking Grant, "Would you not agree, Hugh?"

"That was the aim," he said. "We had to sort of establish all that in one episode before the rug was pulled from under the feet of this adorable couple."

The Undoing airs Sundays at 9 p.m. ET on HBO