Dwayne Johnson was scared to play Mike Kerr in 'The Smashing Machine'

The actor plays two-time UFC heavyweight champion Mike Kerr in Benny Safdie's upcoming film The Smashing Machine, and he recently told Vanity Fair he was scared to take on the role.

"It was very real. I had not experienced that in a very, very, very long time, where I was really scared and thinking, 'I don't know if I can do this. Can I do this?'" Johnson said. "I realized that maybe these opportunities weren't coming my way because I was too scared to explore this stuff … I was so hungry for an opportunity to do something raw and gritty and rip myself open. And all of a sudden, Smashing Machine comes along."