Britney Spears has been called out for sloppy lip-syncing many times in recent years, and especially in the last year since she kicked off her Las Vegas residency.
This could be the craziest example yet, however.
During a video of Saturday night’s "Piece of Me" concert performance at Planet Hollywood, the 32-year-old star struts around, holding her microphone.
While "Britney" is seen crooning to her song “Perfume,” it's actually Australian artist Sia’s voice that is heard booming through the theater in the clip above.
At least according to fans who went ballistic.
Sia was featured on an acoustic version of the tune released in January, and also co-wrote the lyrics, so her connection to the track is well documented.
Still, fans were very far from impressed with Britney Spears lip syncing, even if it's far from news at this point that she does so and not even carefully.