Ke$ha and Alice Cooper join forces for stage duet

Pop star Ke$Ha showed off her rock 'n' roll credentials after performing onstage with Alice Cooper on Thursday (15Sep11).

The metal rocker invited Ke$ha onstage at his concert at the Los Angeles club Whiskey a Go-Go, where he played tracks from his new album Welcome 2 My Nightmare.

The unlikely duo performed Cooper's classic hit School's Out for the star-studded audience, which included KISS guitarist Paul Stanley, Rob Zombie and Rage Against The Machine's Tom Morello.

It isn't the first time the new pals have collaborated onstage - Cooper was a surprise guest at a Ke$ha gig in Norway in July (11).

The TiK ToK hitmaker features on Cooper's latest album on a duet called What Baby Wants.

Speaking about Ke$ha, Cooper recently told Billboard.com, "I met her at the Grammys and I immediately looked at her and went, 'This girl is not a pop diva. She's a rock singer.' She would much rather be the female Robert Plant than the next Britney Spears... There's a little bit of defiance in me... Nobody's going to expect Ke$ha on my album so, great, let's do it. I like the idea you still can't put me in a corner and say, 'This is what you're gonna sound like.'"