Mark Ruffalo says shooting a nude scene with Julianne Moore was "horrible", because he was so embarrassed.

The pair star in new family drama The Kids Are All Right. The movie is about a lesbian couple, played by Julianne and Annette Bening, whose children decide to trace their sperm-donor father, portrayed by Mark. They get on well with him, causing family life to be transformed.

Mark and Julianne have been good friends since appearing in 2008 film Blindness together. Although this made shooting the new movie fun, the pair found the naked scenes tough. "People are like, `How does Julianne Moore look naked?` I don`t know. She was pressed up against me the whole time. I couldn`t look at her," Mark laughed. "OK, we`re naked. That`s horrible for a little while. After a while, we`re naked and you`re like at a nudist beach. And the rest of it is like, you`re wrestling nude..."

Julianne and Mark shot their scenes over three days, and were eventually thankful they know each other so well. Both have had to film love scenes with someone they have only just met, and found the experience tough.

"You do spend a lot of time chatting somebody up. `How many kids do you have? Where do you live?`" Julianne explained.

"And to do that naked, with someone on top of you, in between takes? That`s really awkward. I`ve had that experience," Mark added.

Mark and Julianne`s partners were not intimated by their nude scenes, with the pair explaining it was actually Mark`s wife Sunrise Coigney who convinced him to take part.

He was initially worried he wouldn`t have time to shoot it as he was so busy, but Julianne stepped in and asked Sunrise to convince him otherwise.

"She was like, `Whatever happened with that movie you were doing?` And I said, `Mark said he can`t do it because he doesn`t want to be away from you guys and he`s been working so much.` And she said, `That`s crazy, I like that movie. I don`t care if he goes away,`" Julianne told USA Today.
sections: Celebrities