Patrick Stump's new sound is heavily soul-based, so it made perfect sense when the Fall Out Boy frontman treated Lollapalooza attendees to a medley of '80s and '90s R&B hits during his set last Saturday.

Stump, who plays all the instruments on his upcoming solo debut 'Soul Punk,' moved behind the drum kit for the medley, which began with Montell Jordan's 'This Is How We Do It.' "To all my neighbors, you got much flava," Stump sang as the crowd danced along.

The music moved seamlessly into Bobby Brown's 'Every Little Step,' followed by Stump and his band harmonizing on Boyz II Men's 'Motownphilly.' Finally, Stump warned, "Never trust a big butt and a smile" when he ended the medley with Bell Biv Devoe's classic hit 'Poison.'

Stump has been incorporating unexpected covers into his concerts this year, with Kanye West's 'All of the Lights' making frequent appearances in the set list. Check out a fan-shot video of Stump's Lollapalooza medley below.

Watch Patrick Stump Perform an R&B Medley at Lollapalooza