PHOTOS: Britney's 'Piece of Me' Opens in Vegas

Britney Spears performed two-dozen of her hits, and danced through much of the spectacle, during the Friday night opening of her new Vegas show, Piece of Me.

Dropping into Planet Hollywood's Axis Theater from a giant globe, Brit tore into "Work Bitch" with alien dancers surrounding her. She changed outfits, and wigs, half a dozen times, ran up and down stairs, suspended herself from the ceiling dressed as a giant angel, swung around a massive tree, and, in a slightly bizarre move, walked Saved by the Bell and Extra star Mario Lopez around with a leash. Spears's set list was impressive, including everything from recent releases like "Perfume" to classics like "Toxic," "I'm a Slave 4 U," and, of course, "(Hit Me) Baby, One More Time" (she closed with "'Til the World Ends").

The usual staid Vegas crowd moved to the high-octane show and Britney impressed many with her dancing that became more natural as the show went on. She sang very little, but no one was expecting a Celine Dion performance. All in all, Brit should be very proud of herself. Click here for more information on Piece of Me and see more pics on opening night on the following pages.