Britney Spears News: The pop princess is caught lip syncing again on stage while performing "Perfume", co-written by Australian singer-songwriter Sia, at Planet Hollywood Theater in Las Vegas on Saturday. The segment did not escape the public eye as some audience on the concert managed to take a video and posted it in Instagram which fans called Britneysite. Spear's manager and fans defended the singer.

In the video, the 32-year old pop princess is holding her microphone as if singing however it is Sia's voice heard in the theater. "The 32-year-old pop star struts around and holds her microphone, seemingly singing sweet ballad Perfume - but Sia's voice is booming through the theatre!" reports from Radar Online said.

Earlier reports said that this is not the first time for Britney to be caught lip syncing in her Piece of Me residency. In another Instagram post that dates back February, another video featured Britney dancing, her mic flying off her waistband, but still her vocals can be heard on stage.

Spear's manager Adam Leber released a counter statement in June saying that it is impossible for the singer to sing and dance 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. 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." Leber said.

Some Britney Spears fans also posted comments on Instagram defending the pop princess. Others proposed another explanation that the act is 'an accident' and there might be technical difficulties in the concert resulting Sia's voice to be played louder than spears.  "Only this time it (the guide track) was put into the house mix, making for an embarrassing accident," one fan commented.

"Sia is the back up singer in the chorus. What's the big deal?" another fan said.

In an interview on Chicago's 103.5 KISS FM, the Work Bitch singer promised she will be singing live. "I'm definitely going to be singing live,' she told 'I always sing live. It doesn't sound so great all the time, but I do my best."

Meanwhile, after Britney's performance in Las Vegas, she tweeted, "Incredible night getting to do what I love! Thx to everyone at the show tonight. Hope y'all had as much fun as I did!"