Simon Cowell has revealed in a new interview that he advised Cheryl Cole to "raise you game" just days before her shocking exit from X Factor USA. 

The music mogul told The Hollywood Reporter that he warned the 'Promise This' singer that she may not cut it in America and wasn't surprised when her move fell through:

"I said: 'Cheryl, you've got to raise your game a bit. This is America, it's a much tougher market.' I came to the conclusion that she may not be as comfortable here because I was seeing a different person."

"She was like Princess Diana when she would walk out in England, and I accepted the fact that people didn't know her here, but I think it did have an effect on her."

He added that there were negotiations to find her a role on the new UK season, but her demands became too high:

"We had gotten to the point where she wanted my dressing room."

Watch the official preview for X Factor USA below: