'West Side Story' star Rachel Zegler talks friendship with Steven Spielberg

The new "West Side Story" doesn't just give us an updated version of a beloved classic, it introduces us to one of Hollywood's most talked-about newcomers: Rachel Zegler.

Zegler plays leading lady Maria in director Steven Spielberg modern take on the musical. This role was originally brought to life on the big screen by the late Natalie Wood in the 1961 movie version and by Carol Lawrence in the 1957 original Broadway run.

The 20-year-old told "Good Morning America" she responded to a casting call on Twitter and sent in what she called "the worst self-tape one could possibly send in."

"I hope it never resurfaces on the internet," she said of the clip. "I'm sure it will, and it'll be a terrible day for me online."

Whatever was on the tape clearly worked for her, as Spielberg eventually offered her the role after an almost year-long audition process. She accepted, but asked the filmmaker if she could still do "Shrek: The Musical" at her high school. He agreed to the request.

Zegler called Spielberg "such a wonderful friend and mentor;."

"Whenever anything exciting happens ... he's the first person I go to," she said. "With the time that we spent together on this film there was just so many awesome conversations about our favorite movies and our favorite musicals."

Zegler called meeting Stephen Sondheim, the Broadway legend who wrote the lyrics for "West Side Story," during recording sessions for the movie's music "an incredible honor." Sondheim died Nov. 26 at the age of 91.

"Getting to be in the same room as Stephen Sondheim is something we can never forget, we can never outdo. It's something that I will certainly hold in my heart for the rest of time," she recalled of their time together. "We miss him desperately."

Part of the draw for Zegler to play Maria in "West Side Story" was getting to play a character that had been "reinvented" in a script from Tony Kushner.

"She's not the ingénue you remember," she teased of her portrayal of Maria. "She has a lot more agency and she's very strong and it's very important for Latinas to see that onscreen."

"Something's Coming: West Side Story," a special edition of "20/20," will air on Sunday, Dec. 5 at 7 p.m. ET on ABC, streaming next day on Hulu.