At one point in “La La Land,” the elaborate dance numbers literally lift the story’s star-crossed lovers off their feet.

When he directed his homage to Los Angeles and its creative dreamers, Damien Chazelle knew that the dancing would be just as critical as the music in moving the story forward. He met with nearly 40 choreographers to find the right fit.

One of them was Mandy Moore, who came recommended by both helmer David O. Russell (having choreographed three of his films) and “So You Think You Can Dance” creator Nigel Lythgoe (she garnered four Emmy nominations for the show’s routines).

After a two-hour meeting to discuss scene breakdowns and visions with Chazelle, Moore got the gig. Brought on before casting concluded, she spent several months with the director, dissecting songs, workshopping ideas, and building upon mutual concepts.

“The process of collaboration was beautiful. Ideas would usher ideas,” says Moore. “It was really inspiring to work that way.”

In pre-production, Moore privately tutored leads Emma Stone and Ryan Gosling. She became their athletic coach for six weeks, recommending Pilates and overseeing their daily strength training. She instructed them on how to be graceful and fluid in many styles, including jazz, tap, and waltz. And in addition to their physical training, she trained their minds to explore the passion of dance.

“I wanted to teach them how to listen to music, coordinate their bodies, move their limbs,” says Moore. “Then we focused on the textures of the steps.”

Following the private tutorials, Moore had six weeks remaining to refine routines. She worked closely with all department heads, including scouting locations with production designer David Wasco, finessing color palettes with costume designer Mary Zophres, and reviewing camera framing with DP Linus Sandgren.

The film’s opener — a spontaneous-looking, Jerome Robbins-esque jazz sequence that erupts during a traffic jam on freeway ramps — was particularly complex. Cars were placed at specific distances from each other and camera movements established. Moore hired 30 professional dancers, chosen for their athleticism and sense of timing.

The scene required prop work (slamming doors), intense physicality (jumping on hoods and roofs), and a keen sense of rhythm. To extend the routine miles down the highway, the dancers also performed the sequence against a greenscreen, and the visual effects department tacked that onto the end of the scene.

For the sequence in which the leads waltz in the air against the Milky Way, she worked with stunt coordinators to create graceful movements despite the cumbersome harnesses and wires the actors wore.

Equally complex was the tap number the two perform on the asphalt of a sloping hill. The playful routine emphasizes the couple’s budding romance and was shot in one long take without additional coverage to cut to.

“They were so open to movement and dance,” Moore says. “They were vulnerable and really took a gamble.”