In hopes of the ACMs being more genre-bending (aka pop-driven), Steven Tyler took the stage with Carrie Underwood, both singing each others' hits, 'Undo It' and 'Walk This Way.'

Dapper in an all-white suit, Tyler appears on-stage in the second verse of Underwood's No. 1 country hit 'Undo It.'

"Now your photos don't have a picture frame / And I never say your name and I never will / And all your things, well I threw them in the trash / And I'm not even sad," he croons.

But what may be even more impressive, is Carrie holding her own on the Aerosmith hit, 'Walk This Way.' Fittingly sporting a more rocker black-and-silver short dress and magenta hair extensions, Carrie takes the lead halfway through the song: "Seesaw swingin' with the boys in the school / and your feet flyin' up in the air," she belts, leaving all of the high notes to Steven, who can still unleash them like he did 20 years ago.

Tyler and Underwood even attempt an onstage kiss! Although, let's face it, it was much more G-rated than Madonna and Britney Spears infamous MTV VMAs make-out sesssion.

Watch Steven Tyler and Carrie Underwood Perform, 'Walk This Way' at the 2011 ACM Awards

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