Chrissy Teigen Freaks Out Over *NSYNC's Surprise Performance at Justin Timberlake's L.A. Concert: Watch

Chrissy Teigen's fangirl side came out when she attended Justin Timberlake's concert in Los Angeles on Wednesday, March 13.

While the vocalist's recent shows have featured only JT himself singing his old and new solo tunes, he turned his most recent performance into an *NSYNC reunion, with his old bandmates joining him on stage.

"Oh my f------ god," the mother-of-four captioned an Instagram Story video that showed the "Cry Me a River" crooner with Lance Bass, JC Chasez, Chris Kirkpatrick and Joey Fatone.

The model's jaw dropped at the reunion, and she filmed herself and husband John Legend in the crowd as they sang to hits like "Girlfriend," "Bye, Bye, Bye" and "It's Gonna Be Me."

The Cravings cookbook author said she was "dead" over the boyband's performance, as she revealed their song "That's When I'll Stop Loving You" was her "first dance."

The men also sang their new track "Paradise" — which is featured on Timberlake's upcoming album — live for the first time.

The group also recorded the tune "Better Place" last year for the Trolls Band Together soundtrack.

"That was fun. It's kind of crazy, like, there's so much that just picks up right where it left off as far as the chemistry," Timberlake said of working with his pals again after a long hiatus.

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"Growing up in the industry and getting access to so much in the studio, I just became like a studio rat," he continued. "I just loved being in there and I loved the creative process. And also, as it pertains to harmonies, I spent some time with four other guys doing a lot of harmonies."

Fatone exclusively admitted to OK! that he was pleasantly surprised by the public's response to their reunion.

"People are listening and loving it, which is great. It's weird. It's as if we died and came back to life," he quipped. "It's odd. I didn't think it was going to have the magnitude it had."

"People are obviously yelling and screaming for a tour, but there's a lot of things that come into play before that could happen," he admitted of the group's future. "There's five guys — some of us are married, some have kids, some may not want to do it. We have to have that conversation and talk about what we do now that the song is out there."

Timberlake's solo Forget Tomorrow World Tour kicks off next month, with his album, Everything I Thought I Was, debuting on Friday, March 15.