NEW YORK — You haven't really arrived on Broadway until an image of your grinning face goes up on a massive billboard.

It is a joy Jordin Sparks has yet to savor.

"I haven't gone to Times Square to stand there and actually look at it yet," the 20-year-old singer says of her 34-foot-by-20-foot image that hangs in front of millions of passers-by. "I'm nervous people are going to see me staring at me and then go, 'OK, she's a weirdo.'"

There's little risk of that: Four years after winning "American Idol," Sparks comes across as bubbly but carefully poised as she makes her Broadway debut in the 2008 Tony Award-winning musical "In the Heights."

"It's gone by so fast that I have to literally sometimes tell myself to stop and think about it. Now I have my name on a dressing room on Broadway," she says during an interview in the Richard Rogers Theater. "How did I get from there to here so fast?"

The quick answer is: Beat Blake Lewis for the Season 6 "Idol" crown, put out two CDs, pump out a few huge singles such as "No Air" and "Battlefield," and then find yourself in a meeting with producers who think you might be the perfect person to step into the role of 19-year-old Nina Rosario in the joyous, Latin-laced musical.

"I saw the show and I was just completely captivated. I'd never seen a musical that was so current. I fell head-over-heels in love," she says. "I literally did not take that soundtrack out of my CD player for four months."

The Arizona native says she's enjoying living on her own for the first time and staying put in one place after years of touring. She's moved into a Manhattan apartment with her two small, mixed breed pooches — Maggie and Miles — and can finally unpack.

It's not an understatement to say Sparks has thrown herself into her new role. Late last month, she pulled a few muscles in her hip and had to held back for four shows while she underwent acupuncture and physical therapy.

The injury happened while she was on stage early in an evening performance of a two-show day. During intermission, she told producers she was having trouble walking. They offered to pull her — but she insisted that the show must go on. "I was like, 'No, no. We need to continue the story. That break in the continuum will mess people up.' So I finished the second act," she says.

"When I do something, I just sort of dive in headfirst," she says. "I've never lived here in New York City so I've never walked back and forth from places — doing the dancing, different things, all the choreography and eight shows a week — my body wasn't used to that."

Sparks admits she's had to work overtime to keep up with the professional hoofers — a recent performance showed her growing pains — but it's obvious she doesn't need to worry about one thing: her voice. She belts out powerful, crystal-clear notes that would make even Broadway singers envious.

"She unlocks this thing inside of her and it's pretty remarkable to let it wash over you," says the show's director, Thomas Kail. "She's so incredibly prepared and dedicated and wants to be excellent. That's what she brings to everything."

Sparks had hoped one day to bring her voice to Broadway, just not so soon. The daughter of former NFL player Phillippi Sparks, she recalls seeing plenty of shows while her dad played for the New York Giants. Her favorite was "Smokey Joe's Cafe."

"I walk in to the stage door every day and I'm like, 'I get to do this. This is my job,'" she says. "I say that about music as well. I can't believe I get paid for doing what I love to do."

It might not have happened if it wasn't for "Idol," which she says she still watches, and she still votes. This coming season — its 10th — promises to be very different, with all but Randy Jackson having left the original judging panel and the show facing stiff competition from "America's Got Talent" and Simon Cowell's "X Factor." Front-runners to fill the judges chairs are Jennifer Lopez and Steven Tyler. (The show will announce the new judges next Wednesday.)

In 2007, Sparks became the youngest winner in the show's history. That led to everything — the albums, a tour with the Jonas Brothers, singing for President Barack Obama and winning an American Music Award.

"It still feels like yesterday. I still hear my heart beating in my ears and seeing people clapping and screaming," she says. "I can't wrap my mind around it."