Matt Damon has Mars to blame for missing out on Manchester by the Sea.

The lead role won Casey Affleck an Oscar Sunday night and director Kenneth Lonergan an award for Best Screenplay.

But in a cruel twist of fate, the Best Actor prize might have been Damon’s had he taken the role of Lee Chandler.

Manchester by the Sea was originally set up with Damon in the starring role (he was also briefly slated to direct). He gave the part up to Affleck after agreeing to star in The Martian.

“I regretted the moment that I gave it away,” Damon told the Sun in a recent interview. “I regretted that I wouldn’t be able to play the part, but I went into that whole experience with my eyes open. I wanted to see that film get made, and get made really well.

“I said that from the outset. We were making it and we ran out of time before The Martian.”

Damon wanted Lonergan to wait for him, but the director was keen to shoot Manchester by the Sea in early 2015.

“I said, ‘I’ll do it in two years,’ and then Kenny said, ‘But I’m ready now.’ We had always talked about Casey and the only person I could ever give this up to was Casey. I grew up with him and he’s one of the best actors that I’ve ever seen in my life and I love him. Casey and I had done one of Kenny’s plays in London about 15 years ago – that’s how Casey and I knew Kenny. So it felt right; it felt like a circling of that whole thing. The three of us will always be attached to this project; I’m still a producer on it. It just felt absolutely right.”

Perhaps as a foreshadowing, Damon told us that in the end, Affleck was the right actor for the part.

“Having been in this business for a long time, I really have come to the conclusion that the right actor always gets the part. What’s meant to be is meant to be and I can’t look at that movie – I’ve read 20 drafts of it and I’ve seen 10 cuts of it – and I can’t imagine anyone else playing that role. Casey’s just magnificent.”