Britney Spears Works Vegas Debut

Britney Spears kicked off her two-year residency at Planet Hollywood in Las Vegas Friday night and delivered an impressive performance that left many in the audience claiming the pop performer has officially returned to her entertaining ways of old.

Though Spears received some criticism for appearing to lip sync a majority of the songs in her "Piece of Me" revue, the show's incredible costumes, intriguing set design, and intricate choreography - which the performer seemed to tackle with ease - earned the iconic performer thunderous applause throughout the evening.

The Advocate was in attendance along with a long list of celebrity spectators, including Miley Cyrus, Katy Perry, Adam Lambert, Selena Gomez, and Mario Lopez - who Spears dragged up on stage for a playful S&M-themed performance of "Freakshow" in which she spanked her former X-Factor co-star with a riding crop as he crawled across the stage.

"Work Bitch" - the same track Spears told The Advocate earlier this month was inspired because it was "a term of endearment among my gay friends" - opened the show before the performer launched into a steady stream of her biggest hits.

Seven costume changes and a variety of wig switches ensured "Piece of Me" was generously sprinkled with the signature style spectators have come to expect from a Vegas revue while maintaining the persona the pop performer has cultivated over the years.

"I'm going to be extremely nervous the first show," Spears told The Advocate a few weeks before "Piece of Me" was to debut. "But I know I'm just going to put my nerves aside and pull it together."

However, for those in the audience, it was obvious Spears didn't simply "pull it together," she did indeed work, bitch.

View highlights from the show in the video clips and photos below.

Britney Spears PRO SHOT Las Vegas Opening Night... by ladygagaspecial

Photo Credits: David Becker & Denise Truscello