Kevin Bacon joins Billy Joel onstage at Madison Square Garden: Watch here

The two sang "The Entertainer" and "You May Be Right."

The special guests who join Billy Joel onstage during his Madison Square Garden residency shows tend to be fellow rock stars -- but at his Aug. 29 show, Joel welcomed a man better known as an actor: Kevin Bacon.

In addition to starring in classic movies like "Footloose" and TV shows like "The Following", Bacon is an accomplished musician, having been in a band with his brother Michael Bacon, aptly named The Bacon Brothers, for decades.

Given Bacon's music background, it wasn't surprising to see him stroll onstage Tuesday, guitar in hand, to join Joel for a rendition of his 1974 track "The Entertainer."

The duo also duetted on Joel's 1980 classic "You May Be Right."

Joel's next Madison Square Garden show is Sept. 10, and he's currently touring stadiums with Fleetwood Mac's Stevie Nicks.

The "Uptown Girl" singer announced in June that he will be ending his Madison Square Garden residency with his 150th lifetime concert at the historic New York City venue in July 2024.

Throughout the years, since his first performance there on Dec. 14, 1978, he has been joined onstage by everyone from rock 'n' roll legends like Bruce Springsteen to up-and-coming artists like Olivia Rodrigo, and now Bacon.