Michael Keaton thinks 'Birdman' is revolutionary.

The 63-year-old actor has praised the comedy - in which he stars as protagonist, Riggan - for being innovative and making filmmakers reconsider how they make movies.

He said: '''Birdman' has kinda ... changed things.

''I'm not saying you won't see traditionally-made movies any more. But I've had meetings with directors and they've said it makes them rethink everything.''

The movie also stars Zach Galifianakis and Emma Stone, and has already been nominated for seven Golden Globe awards, which Michael thinks is down to the fact everyone is talking about it.

He added: ''You can hate this movie but you have to talk about it. It's going to go down as one of the most interesting movies ever made.''

However, the 'Beetlejuice' star admitted he had his preconceptions when making the movie because of the way in which it was filmed, which creates the illusion it was all shot in one take.

He explained: ''There was a part where Zach Galifianakis and I were saying, 'Why don't we make the movie the normal way? Why are we doing it like this?' Then you see it and ... woah. At about minute four or 11 you feel that door shut and you go, 'OK, now I'm in. There's no getting off.' ''

Despite his initial apprehension regarding the concept, the acclaimed actor revealed he was desperate to be part of the movie when he found out it had been written by and would be directed by Alejandro González Iñárritu, because he is such a huge fan of the movie mogul's 2000 movie 'Amores Perros'.

He told The Guardian newspaper: '''Birdman' is a very risky movie. I knew I wanted to do it just from watching Alejandro's other work. I told a friend, 'I would have done it based on 'Amores Perros' alone.' And he said, 'I would have done it based on the car crash in 'Amores Perros' alone.'

''But as an actor, you'd be a lot safer in his other movies with all their different stories. In this one, there's nowhere to hide.''