"Breaks my heart to share this news. After hurting my ankle last night my doctor has advised me not to perform this weekend," she said in an Instagram post. The shows are expected to be rescheduled.
The seriousness of the singer's injury is still unknown, but this isn't the first time she's been hurt on stage. In 1999 Spears underwent knee surgery from a rehearsal injury; in 2004 she hurt her knee again during a video shoot.