Jesse Eisenberg wrote The Debut lead role with Julianne Moore in mind

Jesse Eisenberg wrote the lead role in The Debut specifically for Julianne Moore.

The 42-year-old star has written and directed the musical comedy flick - which centres a shy woman who loses herself in the world of theatre after being unexpectedly cast in a production of an original musical - and confessed that he would have been "screwed" had the Far from Heaven star declined a part in the flick.

Speaking at the Karlovy Vary International Film Festival in the Czech Republic, Eisenberg said: "I was thinking, 'If she doesn’t do this movie, it won’t get made, because she’s the only person on the planet who could do this thing.' Which is a mistake as a writer. You don’t write for a movie star because chances are they’re busy, or don’t want to do it, and then you’re screwed. But with this, I was like, 'I will only do this movie if Julianne says yes.'

"And I was so scared halfway through the script. I was telling my friend, 'God, this is so awful, because only one person could do this part — and if she doesn’t like it, I’m screwed.' So, it’s for her, but it’s also about my own experiences."

Eisenberg also rejected speculation that the movie is a musical.

The Social Network actor said: "No, the movie is not a musical in the sense that the characters break into song. The movie is about this woman who gets a part in a musical, and so you see her rehearse for it and you see her opening night. But no, it’s not a straightforward musical, which I think the movie studio is happy about."

Eisenberg's previous directorial effort A Real Pain - in which he and Kieran Culkin played mismatched Jewish cousins who embark on a tour of Poland in honour of their late grandmother - was acclaimed by the critics and won several awards, although the star explained that he was trying to "humble" himself with an exploration of his family's past rather than earn recognition for the project.

Asked if the picture was therapeutic, he said: "No, because I was celebrated for it! It did the exact opposite. I was trying to reconcile, like, how do I live more responsibly and humbly given my [family’s] past. And then people are like, 'Here’s a tuxedo for free. Please come to this award show.' And suddenly you’re like, 'No, no, no. This is the opposite. I was trying to humble myself.'

"The only good version of that movie is that everybody hates it and I’m miserable again and I’m living on the street and suddenly I have a taste of suffering. But no, it was the exact opposite. They were like, 'You know that movie you made about your guilt for the Holocaust? Come talk to Conan about it!'"