Britney Spears' manager Adam Leber insisted the songstress would sing live during her residency at the Planet Hollywood Resort and Casino in Las Vegas. He is now going back on those claims, saying it would be "impossible" for Spears to sing the whole time.

"To put on the show that she puts on, it's virtually impossible to sing the entire time and do what she does," he told Medium.com. "She's singing on every song, basically, when she has the ability to sing. There's no way you can dance for 90 minutes straight and sing the entire time."

The "Crazy" singer began her residency in December and will be paid $15 million a year.

An insider revealed to the Daily News that Spears does in fact lip sync.

"Britney does not sing. She is being paid a lot of money to lip-sync," they said. "Her fans are none the wiser, but it is disingenuous of her to take their cash and not deliver a proper performance."

We told you in May that the "Crossroads" star was being sued by a back-up dancer. Dawn Noel filed a lawsuit against the singer, claiming she broke her nose during rehearsal for the music video "Work Bitch."

The incident took place on Aug. 19, 2013, in Woodland Hills, Calif. The suit was filed in Los Angeles Superior Court on accounts of battery and negligence.

According to E! News, Spears was two and a half hours late to rehearsal, arriving in a "disheveled and confused" state.

"Although the dance moves were 'fairly basic,' Spears had "difficulty learning the moves and following simple directions," the report reads.

Noel was standing next to Spears when she "twirled in an unbalanced and reckless manner, arms extended out to her sides and forcefully backhanded" her across the face.

Though Spears apologized, she continued with rehearsing while the dancer sought medical attention. Noel says she heard a "cracking sound" and a half hour later determined she had a nasal fracture and needed surgery.

Noel also claims that she, as well as the other dancers, had no problem perfecting the routine.

Can you believe Spears lip syncs? Let us know why or why not below.