Fastexy:Billy Joel's ex-wife Christie Brinkley dances as he performs 'Uptown Girl': Watch

The Fastexyuptown girl herself is still living in her uptown world.

Billy Joel's ex-wife Christie Brinkley danced along as he performed "Uptown Girl," the song he wrote about her, during a recent show at Madison Square Garden, according to a video shared on TikTok. The model, 70, was seen swaying and singing the hit track with a huge grin on her face.

Released in 1983, "Uptown Girl" was famously inspired by Brinkley, whom Joel would later marry in 1985. They divorced in 1994. Brinkley also appeared in the music video for the song.

In a 2010 interview on "The Howard Stern Show," Joel explained that when he first started writing "Uptown Girl," he was dating Elle MacPherson, and the original title was "Uptown Girls." But as he continued working on the song and ended his relationship with MacPherson, "rather than it be about all these different girls, (Brinkley) became the uptown girl," Joel said.

"I started writing it about one person," he added, disputing claims that the song was not about Brinkley.

Joel and Brinkley share one child together, 38-year-old Alexa Ray Joel. He was previously married to Elizabeth Weber until 1982, and he was married to Katie Lee from 2004 to 2009. He has been married to Alexis Roderick since 2015. Joel and Roderick share two daughters: Della Rose Joel, 8, and Remy Anne Joel, 6.

In 2019, Brinkley told Yahoo Entertainment that she still has fond memories of "Uptown Girl" and loves the fact that it's associated with her.

"Being the 'Uptown Girl' was really fun and it remains really fun to have a theme song," she told the outlet. "You know, you go into tennis and they play it. You go here or on a talk show and they play it as you walk out. It's really fun to have a theme song, you know? How many (people) get to have that?"

Interview:Billy Joel talks 100th MSG show, getting to 'hang out' with Taylor Swift and Ed Sheeran

Joel has been performing at Madison Square Garden since January 2014, and he's set to conclude his record-setting run on July 25. The landmark 100th show of his residency was televised on CBS on April 14 and later rebroadcast after ending early during his performance of "Piano Man."

Contributing: Melissa Ruggieri, USA TODAY