Is Britney Spears going to be lip-syncing in Vegas?

Britney Spears is reportedly being paid as much as $300,000 per performance as the newest resident performer at the Planet Hollywood Resort & Casino -- which could be why she's doing everything she can do to dispell rumors that she won't even actually be singing.

A source recently told the New York Daily News that Spears "does not sing" when she performs, adding that she hasn't actually "sung live in a couple years."

With ticket sales of her two-year Vegas engagement threatened by the rumor, Spears and her camp have been emphasising that lip-syncing is not an option.

"I'm definitely going to be singing live," Spears told a Chicago radio station over the phone.

"It doesn't sound so great all the time, but I do my best," she noted.

Spears's manager, Larry Rudolph, told Billboard the same thing.

"She's going to be singing live," Rudolph stated, though he did add that "No matter what anyone says, there's not a single artist who goes out there and does full choreography and is singing without a vocal track underneath them at the same time. It's physically impossible."

The singer's Las Vegas engagement debuts on December 27.