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Simon has revealed exactly what happened when Cheryl left the US X Factor.
Simon Cowell says he came to the conclusion that Cheryl wasn't "comfortable" on the US show as she was unusually quiet during the early recordings.
Simon even gave Cheryl a bit of a pep talk to try and fix the problem but fears she was feeling the pressure through being relatively unknown in the States.
"I said, 'Cheryl, you've got to raise your game a bit'," The X Factor boss revealed.
"'This is America, it's a much tougher market'."
After the decision was made for Cheryl Cole to leave the US show, Simon was in talks with her to rejoin the UK show, with a pay rise and even offering her his prized dressing room.
But when Cheryl missed the initial deadline Simon set and Nicole Scherzinger was announced as her US replacement, Simon called will.i.am to try and sort things out.
"I asked will.i.am, 'How does she feel about it?' He said, 'It's none of your concern.'" Simon told Hollywood Reporter.
"Then I got nervous. I called back to tell him, 'If she wants to come back she's got the gig, but if I didn't hear from her by Sunday, the deal's off.
"I never heard from her. I think her silence was quite damning."
Yesterday Simon's mate Louis Walsh said he'd like Cheryl Cole to perform her new single on The X Factor, but it's still unknown when Cheryl plans to reveal her new single or album.