Cheryl Cole has hired celebrity trainer Tracy Anderson to get her into top shape before the American 'x factor' starts.

The singer has just been confirmed as a judge on the new version of Simon's Cowell's pop star search show and is so determined to impress US audiences she started working out with Tracy - a favourite of Gwyneth Paltrow, Jennifer Lopez and Jessica Simpson - just hours before filming her first episode of the show yesterday (08. 05.11).

A source told the Daily Mirror newspaper: "Cheryl works out anyway but she knows that Los Angeles celebrities have a completely different health and fitness ethos.

"A few weeks back, Cheryl arranged to take lessons with Tracy after Derek Hough introduced them. She wants to make sure she's fighting fit and ready for the US 'X Factor' - and the American audience - and she wants the best in the business for it."

Cheryl joins Simon, L.A. Reid and Paula Abdul on the judging panel of the show and although Paula claims she cannot wait to work with the British star, saying "I'm excited I get to meet her, I've heard such lovely things about her," Simon has already hinted there will be rivalry between the two female judges.

He said: "You put pretty girls together it's like three cats in a sack, isn't it. And it needs a bit of a shake."