(Cover) - EN Showbiz - Ashton Kutcher couldnt believe it when his co-star Kevin Kline pranced down the street topless.

The 33-year-old stars alongside Natalie Portman in new movie No Strings Attached. The plot follows two friends, Adam and Emma, who see if it is possible to have a physical relationship without developing romantic feelings. Kevin also appears in the film, playing Alvin - the father of Ashtons character. Ashton has revealed he loved working with Kevin as he had no qualms about stripping off and flashing his flesh during shooting.

The first day I was working with him hes got these linen pants on, shirt and between scenes hes taking his shirt off prancing down the street, Ashton told Cover Media. Im thinking... hes really going for it. I thought he was going method, I think he was just being Kevin.

Ashton went on to explain he has been a fan of Kevins movies for many years. The hunk was thrilled when he discovered the 63-year-old had landed a role in No Strings Attached and admits he was worried about impressing his co-star.

I was a little nervous about working with Kevin, he added. This guy just loves being an actor, he shows off.

No Strings Attached is released in the UK on February 25. (C) Cover Media