During the Friday, October 29, performance in Los Angeles, the 68-year-old musician enlisted the “Bad Guy” songstress, 19, to play Sally opposite his Jack Skellington, whom he voiced in the film.

In clips posted via YouTube, the California native sang “Sally’s Song” for the Band of California Stadium crowd before duetting with Elfman on “Simply Meant to Be.”

“And now it is my great pleasure to announce a very special guest star, singing the part of Sally, please give a warm, not bad, welcome to Miss Billie Eilish,” Elfman told the packed crowd of attendees before Eilish stepped out onstage wearing a Sally-inspired costume.

Fans couldn’t get enough of her electric rendition, with one tweeting, “billie eilish singing sally’s song was so cute,” alongside a video of the performance. Another social media user noted, “Okay yes, @billieeilish as Sally was perfect!”

Ahead of the performance, the Grammy winner noted her elation to be a part of the show, writing via Instagram, “peeing my pants i’m so excited,” alongside a snap of the sign on her dressing room door.

Hours later on Friday, she shared a photo of Sally from the film via her social media page, captioning it, “my dearest jack.”

The concert spectacular also featured actor Ken Page reprising his role as Oogie Boogie for his character-titled song, as well as Paul “Pee-Wee Herman” Reubens and “Weird Al” Yankovic joining Elfman for a rendition of “Kidnap the Sandy Claws.”

Released in 1993, the Disney movie follows Jack Skellington — the King of Halloween Town — as he discovers Christmas Town. However, his attempts to bring the winter holiday to his hometown causes confusion for his neighbors.

TheTim Burton’s The Nightmare Before Christmas live-to-film concert experience brought the film’s classic songs to life in new ways and also featured on-site trick-or-treating and a pre-show costume contest. A second night of the show will take place on Halloween on Sunday, October 31, at the Los Angeles venue.

Other fans couldn’t help but gush over the entire event, writing via Twitter, “Just saw Nightmare Before Christmas with live orchestra and singers and Danny Elfman treated us to an encore and then a surprise one song rock concert!  It was awesome!!”

Another quipped via Twitter, “The Nightmare Before Christmas live-to-film concert was amazing. An amazing cast (all the love to Ken Page, @peeweeherman, & @alyankovic), f—king @billieeilish as SALLY… and the ever brilliant @dannyelfman just across the board. Finishing with ‘Dead Man’s Party’… incredible.”

This story originally appeared on: US Magazine - Author:Miranda Siwak