Calvin Klein - Kellan Lutz At Ease With Underwear Ads

Kellan Lutz was "completely at ease" stripping down to his underpants for Calvin Klein's new underwear ads.

The 'Twilight Saga: New Moon' hunk - who stars alongside 'True Blood' actor Mehcad Brooks, Spanish tennis star Fernando Verdasco and Japanese athlete Hidetoshi Nakata in the sexy campaign - said he was comfortable about exposing his body because the designer underpants "hold everything in".

He revealed: "You know I've done other fittings where you have to wear underwear and you're kind of uncomfortable because they look funny or it doesn't fit well. They made it really easy. The clothes fit great - there wasn't anything that was riding up, so you don't feel uncomfortable posing."

But the actor - who started his career as a model for Abercrombie + Fitch - did admit to having doubts after the campaign had been shot.

He joked to usmagazine.com: "But now my nude a*s is going to be all over the billboards, we'll see what my mother thinks!"