Britney's back -- and she's working, bitch.

The 31-year-old has been gearing up for her Las Vegas show at Planet Hollywood , and now she's giving fans a sneak peek on the set of her upcoming track "Work Bitch ."

On Sunday, Spears posted a photo of herself in a tiny blue bikini , and sky-high sparkling heels, to her Instagram account, which she captioned:

"Gonna get my tan on in the desert in between shots on the #WorkBitch set today. It's HOT out here people!!!! #desert #heatwave #WorkBitchDay2"