The singer was in the middle of her song "Circus" when the back of her costume came undone. However, Spears remained ever the professional and continued to strut her stuff onstage as a back-up dancer came to her rescue and secured the zipper.
The singer kicked off her two-year residency, "Britney: Piece of Me," on Friday in front of a star-studded crowd, including Katy Perry, Selena Gomez and Miley Cyrus.
Well, what happens in Vegas stays in Vegas...
not anymore with the internet.