Nicole Scherzinger was exhausted. It was a week since Jamie Lloyd’s new production of Andrew Lloyd Webber’s “Sunset Boulevard” had begun performances, and Scherzinger was playing the lead role of Norma Desmond — the forgotten star of the silent screen whose attempt at a comeback doesn’t end well.

In Lloyd’s stripped-down, psychologically focused production at the Savoy Theater, Norma’s unraveling psyche is the heart of a story that is less about the loss of stardom than the emotional fallout of being passed over while in possession of all your gifts. At the end of the show the previous night, Scherzinger stood alone onstage, covered in blood and dazed, appearing to hardly register the audience’s wild applause.

“It’s grueling,” she said last week while curled up on a chair in the depths of the Savoy. “But for many years I have been saying I am using a fraction of my potential, and now I feel I have really tapped into that.”

The glamorous Scherzinger, 45, might initially seem like an odd fit for the role of Norma, immortalized by Gloria Swanson in the 1950 Billy Wilder film on which the musical is based. Scherzinger rose to fame as the lead singer of the Pussycat Dolls, a girl group formed in the early 2000s. And though she played Grizabella in a revival of Lloyd Webber’s “Cats” in the West End in 2014, her post-Dolls career has encompassed two solo albums and long stretches as a judge on “The X Factor” and “The Masked Singer.”

Scherzinger herself was taken aback when Lloyd, the acclaimed experimental director, asked to meet and suggested the part some 18 months ago. “There are many roles I wanted to play in musical theater, but this is not one of them!” she said over the course of an hourlong interview. “I wasn’t sure if the idea was flattering or insulting. But Jamie said to me, don’t watch the movie; read the lines, listen to the music. And I fell madly in love with it.”

In a telephone conversation, Lloyd said he first thought about directing a revival of “Sunset Boulevard” during the pandemic, and “immediately thought Nicole should be in it.”

Norma Desmond, Lloyd added, had come to be seen as a role for an older actress. But he wanted a woman “who is in her prime, really brilliant, but has been discarded, just as we talk even now about women over 40 not having the opportunities they should have,” he said. “I felt there was a connection for Nicole, who had extraordinary international fame, but then didn’t have the opportunity to live up to her potential.”

Talking about her career, Scherzinger said that although she had been a shy and awkward child, she had “always had a hunger and a drive.” Born in Honolulu to a Filipino father and a Hawaiian Ukrainian mother, she was raised in a religious and sheltered environment in Louisville, Ky., by her mother and a German American stepfather, whose last name she took.

Although her parents were blue-collar workers with little money to attend concerts or the theater, she grew up singing and loving music (her mother’s family had a musical group called Sons and Daughters of Hawaii). She attended a performing arts high school, acted professionally in Louisville, and studied theater (“Stanislavski and Shakespeare and all that”) and voice in college.

After leaving college early to join an acoustic rock band, Scherzinger auditioned for “Popstars,” a reality series that offered the winning contestants a place in a musical group and a recording contract. Her winning group, Eden’s Crush, was modestly successful, and “it got me out of Louisville,” she said about her move to Los Angeles.

In 2003, she auditioned for the Pussycat Dolls, a former burlesque act reimagined as a sexy singing and dancing girl group. Scherzinger became the lead singer and a household name, with the Dolls selling millions of records on the back of hits like “Don’t Cha” and “Buttons.”

She was famous, but for a woman who “grew up singing in church,” she struggled with the group’s skimpy clothing and sexualized image, and spent over a decade obsessively exercising and battling bulimia. “I wish I could go back and enjoy it, realize this isn’t going to be forever,” she said. “Maybe that’s what Norma feels: It was her youth, she worked so hard, and she can’t get that back.”

The Pussycat Dolls disbanded in 2010, and Scherzinger pursued a solo career with modest success. It was during this time that she performed “Don’t Cry for Me Argentina” (from Lloyd Webber’s “Evita”) as part of a TV special celebrating Lloyd Webber, who, along with the director Trevor Nunn, asked her to join the cast of the 2014 revival of “Cats” on the West End. Scherzinger described the experience as transformative (every night “I got to shed my old self and be reborn again”), even though she didn’t stay with the production when the show moved to Broadway. She decided to join “The X Factor” instead, and Lloyd Webber was open about his annoyance.

In a telephone interview, the composer said that he had been disappointed because he believed in her talent and “would have loved to have seen her show Broadway what she could do.” But they remained friends, he added, and was delighted when Lloyd suggested Scherzinger play Norma. “I believe she is one of the most gifted singer-actresses I have seen perform my work,” he said. “It’s a tough role, but Nicole is fearless musically and dramatically. I am a total fan.”

Scherzinger said that “The X Factor” had given her the time and financial stability to pursue her own music, which she did while also taking on other projects, like voicing the character of Sina in “Moana,” and starring in a television version of “Dirty Dancing.” But she always believed, she said, that she would return to musical theater, particularly after performing in the television special “Annie Live!” in 2021.

Now that she’s back onstage, how does it feel? She said that preparing to play Norma had been cathartic: “I felt I knew exactly this feeling of abandonment, the constant thread of loneliness, the insatiable need for affirmation, validation. Now, there is this epic, iconic score to throw all this into and create art from places of torment.”

Lloyd said that Scherzinger was “constantly searching, questioning, finding details, deepening her understanding of the inner world of the character.” Her work ethic (asking questions, taking notes and working through breaks), he added, has been an inspiration to the entire cast. “You would never know, through this entire process, that she didn’t have an acting background.”

Asked about future plans, Scherzinger said her dream was to write her own musical, loosely based on her life.

“After all these years, I finally have the courage not to worry about what others think, to know I have something to say,” she said. “As Jamie always says, ‘You are brave, be braver.’”