The Toxic and Circus singer took a tumble on Wednesday during one of her Britney: Piece of Me residency concerts at Las Vegas's Planet Hollywood resort and casino.
"Britney injured her ankle during her performance Wednesday evening and her doctor has advised her not to perform Friday and Saturday evening so that she may heal," Caesars Entertainment, which owns Planet Hollywood and resorts and casinos, said in a statement.
Spears, 33, told her fans on Twitter she would reschedule the May 1-2 shows.
The former child star and X Factor judge began a two-year residency in Las Vegas in December 2013.
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