Beyonce Knowles credits jazz legend Etta James with giving her the guts to record her new album - because playing the troubled icon for a film made her "fearless".

Knowles stars as the iconic singer - who battled numerous drug addictions throughout her life - in new movie Cadillac Records.

And she admits the icon's imprint unhinged a new side of her for her new double disc I Am...Sasha Fierce.

She says, "The music I made before and after the movie were very different. I was a lot more bold and fearless after I played Etta James, because of course some of the character stays with you. Some of the music I would have been afraid to make, I wasn't. I got more guts, more confidence as a human being.

"I think that's why I love doing movies so much, because it's not just an art form. It changes my life and my music and the way I look at things... after playing her and singing her songs, I thought, it's time for me to challenge myself and do whatever I'm inspired to do."