Britney Spears knows "you better work b----" — but discovered hard work has its limits when she injured her ankle during Wednesday night's show in Las Vegas, according to ABC News.

The pop star is currently in residence at Planet Hollywood Hotel & Casino doing her "Piece of Me" show. While performing 1999's hit "(You Drive Me) Crazy," Brit-Brit high-kicked in heels before stumbling and hurting her left ankle.

Watch Christina Aguilera's spot-on Britney Spears impression on The Tonight Show

According to a statement released by Planet Hollywood, Spears' doctor recommended she take the weekend to heal, so she's rescheduled her shows planned for this Friday and Saturday night.

She sent out a few tweets on Thursday night thanking her fans for their understanding.

Later in the night, she issued a mea culpa to fans in the form of a preview for her upcoming collaboration with Iggy Azalea:

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