A singing slip-up on Thursday's episode of The X Factor caused outcry as millions of viewers heard contestant Leroy Bell singing before his microphone was even up to his mouth.

The blunder occurred while the finalists were performing a group number together, but still spawned speculation that the other performances could be faked, which Fox quickly addressed.

"All survival songs are performed live, with just a backing track," an X Factor representative said in a statement to TheWrap.com.

Last week's episode of X Factor saw judges Nicole Scherzinger and Simon Cowell clashed over Cowell's criticism of the contestants Nicole is mentoring.

Now RadarOnline.com has exclusively learned that the bad blood has spilled over backstage!

Cowell, a well-placed source tells us, has been intervening in Nicole's team all week in the lead-up to tonight's show which is the first episode where the viewing public votes.

Five of the 17 remaining acts headed home on Tuesday's live two-and-a-half-hour episode of The X Factor, narrowing it down to the final dozen acts vying for the show's grand prize of $5 million, a recording contract with Sony and a Pepsi Super bowl commercial.

Those sent packing were: Dexter Haygood, Tiah Tolliver, Simone Battle, Phillip Lomax and The Brewer Boys.

The 12 acts left in the competition are: Melanie Amaro, Drew Ryniewicz, Rachel Crow, Astro, Marcus Canty, Chris Rene, The Stereo Hogzz, InTENsity, Lakoda Rayne, Stacy Francis, Josh Krajcik and LeRoy Bell.