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

Dwayne Johnson is opening up about his fears in taking on a more dramatic role.

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."

Johnson also spoke about the process of putting on the prosthetics he had to wear each day for the role.

“I just sat in front of that mirror for three to four hours and watched it all change. There were about 13 or 14 different prosthetics. Subtle, yet I think very impactful,” Johnson said. “By the time I got to set, I was Mark Kerr and I felt it, from how he walked to how he talked and how he looked at life."

While he admits he "is not a big therapy person," Johnson said he had "to be willing to tap into all the stuff that you’ve gone through" in order to take on this part.

"I found it so scary, but also, so nourishing and freeing. I ripped it open,” Johnson said.

The Smashing Machine arrives in theaters on Oct. 3.