Rock outfit My Morning Jacket have never feared the funk, often citing singers like Marvin Gaye, Curtis Mayfield and Prince as influences on their indefinable rock and roll. Last night, the band -- referred to as MMJ by their fans -- introduced their latest album, 'Circuital,' with a concert webcast that streamed live on YouTube ... and funky they did get with the help of R&B's own Nubian Queen Erykah Badu.

Badu joined MMJ for four songs during their three-hour long set -- part of the American Express-sponsored Unstaged series -- from the historic Louisville Palace Theater in Louisville, Ky. They flip-flopped between two MMJ songs -- 'Wordless Chorus' and 'The Day Is Coming' -- and her own songs 'Twinkle' and 'Tyrone.' The two have performed 'Tyrone' together before but this "monster version" of the track, as reported by the Louisville Courier-Journal, "found [MMJ frontman] Jim James on his knees, worshiping the high priestess of soul with an unhinged guitar solo."

'Wordless Chorus' saw James and Badu -- sporting sunglasses, a kaftan and top hat -- partake in a pseudo howling match on the song's, well, wordless chorus. We'll let BoomBox readers decide who they think won in the video of the performance below.

Badu will take the stage for select shows this summer behind her last album, 'New Amerykah Part Two (Return of the Ankh).' She also heads out on the Rock the Bells tour this August.

Watch Erykah Badu Perform 'Wordless Chorus' With My Morning Jacket
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