Oops!... She did it again. The queen of pop suffered a wardrobe malfunction as she kicked off her highly anticipated two-year "Britney: Piece of Me" residency at Planet Hollywood Resort & Casino in Las Vegas.

During the show, most of Spears's body parts were on full display, sporting a variety of revealing ensembles. The pop star exposed even more skin as the malfunction resulted in showing nearly the entire backside of the singer. While giving an exciting performance for her hit song "Circus" on Saturday night, Spears's backside became exposed when her black-and-white striped sequined top became unzipped.

The hitmaker certainly showed her professionalism as an artist as she did not let the outfit accident get in a way of her performance. Instead of getting all flustered, Britney Spears continued to sing as her back-up dancers quickly noticed the unzip and prevented from her top from falling off.

This really could have been a major embarrassment for the veteran pop star and the accident also revealed an additional detail: Britney Spears was not wearing a bra at the time.

The star-studded event, which included Miley Cyrus, Selena Gomez and Katy Perry, had other surprises as well. On Monday evening, the former 'N Sync member Lance Bass made a guest appearance on stage during the "Freakshow" portion, where he dressed up with black cat ears, collar and chest harness, and walked around the stage like a chained animal, sticking out his tongue. The same thing was done by Mario Lopez just last week.