Britney Spears has ''chills'' as she prepares for the opening night of her Las Vegas residency tonight (27.12.13).

The 'Work Bitch' singer has been slaving away inside the rehearsal studio to put the final touches on 'Britney: Piece of Me', her two-year residency at Planet Hollywood which launches this evening, and the star performed the show in full for an exclusive audience of family and friends last night (26.12.13).

Britney shared a photo of herself in dance rehearsals on Instagram and captioned it: ''I've got chills. Last dress rehearsal for friends and family before opening night tomorrow.''

The 'Alien' singer later shared a snap of herself from the dress rehearsal, which pictures her in sexy low lighting while sporting a sparkly bikini top and a fedora hat.

She captioned the picture, writing: ''Can't believe the 1st show is almost here!!!#PieceOfMe (sic)''

The 32-year-old pop star will perform over four nights starting tonight before taking a month-long break. She will then return to the stage for a month of shows beginning the end of January.

Britney's set list will include hit songs such as 'Till the World Ends', 'Toxic', 'Slave 4 U', 'Scream & Shout', 'Oops... I Did It Again' and '...Baby One More Time'.