Britney lip syncs "Perfume"... to Sia vocals!

During one of her latest concerts at the Planet Hollywood, Britney Spears was caught lip-syncing again. Only this time, it wasn't even her own vocals she mimed to. The song playing was "Perfume" by Sia Furler who originally penned and sang this tune.

We wonder--- who allowed for this to happen? Listen to the clip above.

source1 source2