Jennifer Garner says she's "very familiar" with Russell Brand's "anatomy".

The stunning actress - who has two daughters with actor Ben Affleck - stars alongside the British actor in new movie 'Arthur' and admits she had to get very close to Russell while filming some of the scenes.

Speaking on David Letterman's talks show, Jennifer said: "He was in his underwear, and they were very handsomely made. It was Russell and me, right behind him, on all fours. We did it over and over again, so I spent two days just right up against it. So I'm very familiar, in my own way, with the anatomy of Russell Brand - and it's good."

In the movie, Russell takes on the titular role - which was originally played by Dudley Moore - and he says there are a lot of differences from the original.

He said: "He's taller by about a foot. And he exists in the contemporary world. And it's the modern world, so we can't bloody well end the movie with him as a drunk. But there's a lot of changes."