Fans who attended a Shadowboxers performance in Nashville got a very big surprise on Wednesday night (Sept. 30).

The pop-funk group consisting of Adam Hoffman, Matt Lipkins and Scott Schwartz has played a monthly residency at the Basement East in Music City since August. According to the band's website, Wednesday night’s theme was “sweet harmony sounds,” and in keeping with that, Reba McEntire came out onstage during a cover of the Dolly Parton classic "Jolene," along with Karen Fairchild and Kimberly Schlapman from Little Big Town.

In one of those moments that would never happen anywhere other than Nashville, McEntire sang lead on the first verse, while Failrchild and Schlapman shared the second verse. The Shadowboxers provided harmonies all the way through the performance, which you can view in the video above.

Afterward, the incredulous band members posted on Instagram, saying, “This is us on stage singing “Jolene” with @reba and @littlebigtown. Don’t really know how else to put it." They also shared a photo from the gig, saying, "So. Cool."

“Well, this was amazing," Little Big Town added via their own Instagram page.

Originally inspired by her husband's innocent fliratation with a red-haired bank teller, "Jolene" was the title track of Parton's 13th studio album, and became her second No. 1 hit in February of 1974. The track is the basis for an upcoming television movie on NBC.

The Shadowboxers' residency at the Basement East will continue through December. On Oct. 29 they will celebrate Halloween by performing Michael Jackson's Thriller in its entirety, and on Dec. 17 they will wrap things up with a full-length set of their own original material.

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