BURBANK, Calif. (AP) — Choreographer Mandy Moore was lying under a car on the hot pavement while more than 100 dancers above her twirled through gridlocked LA freeway traffic during the opening number of "La La Land ."
The sequence was months in the making — the most complicated ever undertaken by Moore, who's been creating routines for TV's "Dancing With the Stars" and "So You Think You Can Dance" for years.
"I'm going to call it hashtag panic attack," the Emmy-nominated choreographer said of the freeway routine, which required dozens of cars, several stuntmen, 30 professional dancers and more than 100 extras to have perfect timing during long takes.
She had to be close enough to call out cues but couldn't be seen on camera, so she hid under a car, watching on a wireless monitor. She could feel the magic from there when they got the shot.
"I still get goose bumps when I think about it," she said.
Creating that show-stopping (or starting) number and the celestial routines Ryan Gosling and Emma Stone perform in "La La Land" wasn't Moore's only role in the dreamy musical. She also spent months personally teaching the stars to dance.
A tribute to Old Hollywood and modern Los Angeles, the film is a love story set to original music, with Stone and Gosling dancing together throughout.
Each started with individual lessons at a small studio in Burbank, California — not far from the restaurant where their characters, Mia and Sebastian, first meet onscreen. Moore began with the same basics she would for any new student: connecting movement to music and repeating classic jazz, tap and waltz patterns. Along the way, she worked to build "a general love of dance" in the actors.
"If these people don't love to dance, they're going to hate me by the end of this... and I know that can't be part of this equation," she said. "They have to love to dance."
Stone picked up the footwork first, Moore said, then focused on style and delivery. Gosling was the opposite.
"With Ryan, he was like, 'I don't know what step you're doing, but if you give me the style...'" she said.
"Her job is to kind of see the diamond in the rough," Gosling said, calling his teacher "a wonderful person and choreographer."
"She's very confident she can get it out of you if you'll stick with her."
Once they got the basics down, Moore put the stars together and taught them Mia and Sebastian's moves, which were based in part on preferences the actors showed during their private lessons. For example, a foot-scrape move that Gosling liked became one of Sebastian's signature steps.
Planning and executing large-scale performances — like the freeway routine — and creating intimate dances that suit real strengths and imaginary characters tapped all aspects of Moore's talents. The opening scene was "big picture, then work on the details," she said, "where Ryan and Emma was very detail (first), then get the big picture."
Moore's story isn't unlike Mia's. Musicals both classic and contemporary — movies like "La La Land" — are what inspired the dancer to leave her small Colorado hometown for Los Angeles after high school.
"It's super cliche," Moore said. "I was 18. I had 500 bucks and my suitcase."
She performed with contemporary dance companies and in film and TV productions before a series of events brought her to "La La Land." She worked with "Dancing With the Stars" judge Carrie Ann Inaba, who introduced her to "So You Think You Can Dance" creator Nigel Lythgoe. Moore's work on that show earned her two Emmy nominations and the attention of a "Silver Linings Playbook" producer, who hired her to create the dance Bradley Cooper and Jennifer Lawrence perform in that film.
For "La La Land" writer-director Damien Chazelle, the most important thing about the choreography was that it be "as much about character as about bodies moving."
"What I told Mandy is that in this movie, dancing, singing and acting are all just one thing — there is no separation between them," Chazelle said. "Ultimately the dancing really emanated from how Ryan and Emma relate to one another."
Moore would love it if the film inspires viewers to discover their inner Fred Astaire or Ginger Rogers — "ballroom dance is very accessible to people who aren't dancers," she says — but she really just hopes people feel the kind of joy watching it that she did working on it.
"I feel like 'La La Land' is the Super Bowl of your career," she said. "For this to happen for dance, for it to happen for me, and choreography, I mean, this is huge, huge, huge. I might need to hang up these shoes after this."
Follow AP Entertainment Writer Sandy Cohen at www.twitter.com/APSandy .
AP Film Writer Jake Coyle contributed to this report.