Oscar Isaac didn't feel awkward shooting sex scenes with Jessica Chastain despite their long friendship.

The 'Scenes From A Marriage' co-stars have been close pals for years but the 43-year-old actor insisted the level of "trust" between them meant they were relaxed on set.

Asked about any potential awkwardness, he told 'The Jess Cagle Podcast with Julia Cunningham': "I don't know, generally. I guess with us, we have a lot of trust in each other.

"We're really in the whole play of the whole thing, it didn't feel that awkward."

Oscar also praised the way the scenes were shot and insisted the repetitive nature of filming more intimate moments can actually be what makes things difficult.

He laughed: "I think also actually having some length of time - you know what can be really awkward in those scenes? When you're kind of having to do one move for a long time.

"Because sex, generally - I've never had it, but I hear it progresses from one stage to the next.

"But because of the nature of some of these, we could have a little story to the lovemaking. So, that was good!"

Jessica and Oscar have been close since acting school, and he admitted it didn't take long for them to become friends.

He said: "We met in school, Juilliard. She was a couple of years ahead of me. I don't remember the first day we met, but she was sort of dating a friend of mine that was in my class.

"We started hanging out and became very quick friends. We just really got along right off the bat and I respect her so much. She really helped me, we were each other's cheerleaders early on."

He likened his on-screen chemistry with Jessica to a pair of flatworms.

The Hollywood star - who has also starred in films such as 'Inside Llewyn Davis' and 'Ex Machina' said: "I was just watching this video of this guy, it’s like a Ted Talk, talking about these little … flatworms. You can cut them into like 100 pieces and they will grow a whole new worm out of the little piece.

"So they’re basically kind of immortal and they’ve been doing work at the cellular level where they’re seeing that the cells kind of talk to each other through electricity and kind of decide, ‘Okay you’re going to make the head. I’m going to make the tail.’ They’re communicating through some sort of like electro kind of magnetic situation.

"If you interfere with these [worms], you can make them grow two heads and they’ll continue to do that. It’s not DNA. It’s just at the cellular level.

"That’s how Jessica and I kind of talk to each other. We’re just like, little flatworms."