It looks like Britney Spears is a hit in Sin City. Her Piece of Me residency show opened Friday night at the Planet Hollywood Resort & Casino to a packed house that was on its feet for the entire 90 minutes.

From her front row seat, Miley Cyrus became part of the show for one number. Mario Lopez was on stage with Brit for another.  Katy Perry, Selena Gomez, and Adam Lambert were also spotted in the house.