Matt Damon has realised actors are not the most important thing about movies.

The 41-year-old star will make his directorial debut on an untitled project next year, and says the decision to move behind the camera came when he realised filmmakers hold the "power" on set.

He said: "When I first started getting work, I felt like acting was the most important thing. But the more you do it, the more you realise that in the end, the director has all the power."

Despite wanting to move into directing, Matt knows he won't be able to cover up mistakes if he is less than brilliant behind the camera.

He said: "There are just too many decisions over the course of too long a time, and if you're not a truly great director, you just can't hide."

While he hasn't directed before, the 'We Bought a Zoo' star already has an idea of the approach he will take after observing how Clint Eastwood worked when they made 'Invictus' and 'Hereafter'.

He explained in an interview with America's GQ magazine: "Clint says all the time, 'Let's not f**k this up too much by thinking about it.'

"That's his approach, and some people love it and some people hate it, but he doesn't do too much hand-wringing about it. I'd love to do what Clint does."