Gwyneth Paltrow was "petrified" about returning to a movie set in Marty Supreme.

The 53-year-old actress is back on the big-screen after a seven-year hiatus in Josh Safdie's movie and admits that she had doubts about whether she would be able to perform at her best.

Gwyneth told Entertainment Weekly's The Awardist podcast: "Acting is so weird. It's so hard to explain how you do it. It's not a skillset that... it's not a trade that you learn and you get onboarded into how to do something.

"It's so weird and ephemeral and kind of magic. So I was like, how did I used to do this? And am I still going to be able to do this? Am I going to be able to access all that stuff and energy and in the moment?"

Paltrow's task was made somewhat easier by the fact that her Marty Supreme character - the socialite and ex-movie star Kay Stone - was preparing for a comeback of her own in the film.

She explained: "It was a scene where (Kay) was on stage rehearsing a play, and the camera was kind of off in the audience. And I learned in the theatre, and so I was like, oh, okay, well I'm on stage and I can just sort of feel my way around here."

The Shallow Hal star continued: "Unfortunately, I haven't done a play now since before I had a kid, so, like, 2002. But I did a million plays, and it was always like my touchstone.

"When I want to feel purpose, when I want to feel the real value and art of what we do, I would always go back and do a play. Right after Shakespeare in Love, I went back to Williamstown and did a play. That's just been my thing. So it was, for me, a really profoundly kismetic thing that my first day back I was on stage."

Paltrow's alter ego forms a sexual relationship with table tennis player Marty Mauser (Timothee Chalamet) in the film and the Goop founder spoke of the importance of "parity" between the two characters.

She said: "It's like game recognises game. 'You're a hustler. I know you. Don't f*** with me, don't try to pull the wool over my eyes.'

"It was very important for me to feel that parity with him so that when they had scenes together, it was almost like a relief that nobody was really in their essence. And it was clear that it was a transaction and she wanted something from him and he wanted something from her, which was kind of another layer of sad, but also there was the ancillary benefit of her, I think, feeling alive again."