Britney Spears's live concerts aren't so live.

According to the Daily Mail, Spears' manager Adam Leber confirmed that the singer has been lip-syncing during her Las Vegas residency performances. Leber explained that the 32-year-old mother of two has difficulties singing and dancing to all the songs in the set list for her Planet Hollywood Resort and Casino show.

"To put on the show that she puts on, it's virtually impossible to sing the entire time and do what she does," Leber admitted in the interview. "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."

Last year, the pop star's publicist assured fans that her client would be singing live and will not be lip-syncing for her upcoming shows.

"I'm definitely going to be singing live. I always sing live. It doesn't sound so great all the time, but I do my best," Spears said.

The singer has been caught several times by fans mouthing the words to her songs. In February, a video posted online showed the former Disney sweetheart not holding her microphone near her mouth as her music track played in the background.

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

Spears' kicked off her residency at Las Vegas's Planet Hollywood on December 27 2013 and is reportedly earning an estimated $30 million for her two-year residency, which will run until 2015. The singer was offered $12 million to extend her residency for two more years.