Cameron Diaz was asked what she thought of Cheryl Cole's performance in the forthcoming rom-com, What To Expect When You're Expecting.

Diaz, a mistress of diplomacy, commented, "I think she did a great job playing herself... awesome actress." Ouch!

However, it was clear the A-lister had a lot of time for the X Factor presenter who was making her screen debut (not including St Trinians 2007) in a cameo role as a talent show judge.

"She brought energy, lots of fun to the set," she added. "We had a blast."

And in a stout defence of her co-star and the problems she had stateside last year, being unceremoniously booted off US X Factor by Simon Cowell after reports that test audiences didn't like her accent, Diaz added, "I understood everything she said."

PICTURES: Cheryl Cole Stands Out From The Crowd, But Not The Carpet, At Cannes

Diaz's co-star Matthew Morrison, who plays her boyfriend in the ensemble piece, added that he was used to coming to London and seeing Cole on the cover of every magazine, so it was fun to meet her - "she was lovely".

Diaz, Morrison, and their co-stars in the film, Chace Crawford, Anna Kendrick, Rodrigo Santoro and Mz Cheryl Cole herself will be on the red carpet in London tonight for the UK premiere... check back here for pics and report. And here they all are in action in the film, in cinemas on 25 May...