Erykah Badu Joins My Morning Jacket Onstage: Watch

To celebrate the release of their sixth studio album, "Circuital," Southern rockers My Morning Jacket played to a sold-out crowd in their hometown of Louisville, Kentucky, as well as a world-wide audience as the concert was streamed live on YouTube.

Of course a big show demands some equally big surprises (I'm looking at you, Arcade Fire and LCD Soundsystem), and concert-goers and online viewers got just that, as R&B singer Erykah Badu joined the band for four songs: "Twinkle" and "Tyrone," which are Badu's own, and MMJ's "The Day Is Coming" and "Wordless Chorus."

This isn't, however, the first time Badu and MMJ have performed together; the band has been playing "Tyrone" live for a while now, sometimes with Badu. Watch videos of last night's performance of "Wordless Chorus" and "Tyrone" below, the former taken from the webcast itself, the latter shot from the crowd, but still worth it for Badu's stunning and soulful wail, and some psyched-out shredding courtesy of MMJ frontman Jim James.

Former "SNL" funny-woman Rachel Dratch also made a guest appearance during the show, but no videos of that have been posted yet.