After Joel handled the song's first verse, the House of Cards actor ambled onstage without any fanfare before the singer gave Spacey a brief introduction. Without missing a note, the song continued with Spacey tackling the second verse.
Over the track's six-minute runtime, Joel and Spacey continued to trade lines. Although Spacey captured the moment with an onstage selfie with Joel, the actor hasn't posted that photo on any of his popular social media accounts.
This wasn't the first time Joel and Spacey have performed together onstage: In November 2014, when Joel was honored with the Library of Congress' Gershwin Prize for Popular Song, Spacey played "Piano Man" alongside Joel, with the actor even showcasing his harmonica chops.
Joel's latest MSG concert also featured a brief tribute to J. Geils, who died earlier in the week, with a snippet of "Centerfold" that was performed in the middle of "River of Dreams."
Joel's recent concerts have featured a wellspring of surprise guests, including an onstage King of Queens reunion between Kevin James and Leah Remini during "She's Got a Way" and a Joan Jett guest spot at Joel's Nassau Coliseum reopening concert earlier this month. At Joel's MSG show in March, the Young Rascals and John Mellencamp joined the singer.