Robert Pattinson was on Valium during 'Twilight' audition

Robert Pattinson must be doing something right in his auditions, but he doesn't fancy himself a pro.

"I'd started to develop this absolute terror of auditions, which I'm sure a lot of actors have, and I could be so enthusiastic about something, and then the day of the audition, my confident would just entirely collapse," the 35-year-old actor explained to GQ as its March cover star. "The same thing happened the morning of the 'Twilight' audition."

Pattinson described living on his agent's couch at the time and saying, "I'm freaking out. I don't want to go to the audition anymore."

He was advised to "find Valium in my bathroom."

"I'd never taken a Valium before," Pattinson continued. "I just remember just feeling so glorious in the back of the taxi with the window open and just being like, 'Wow! This is what I've been missing.' I think I had this sort of quite spacey, detached kind of thing in the audition, which must have kind of worked for the character."

Pattinson starred as heartthrob vampire Edward Cullen in the "Twilight" franchise opposite Kristen Stewart from 2008-12.

Stewart recently reflected on her chemistry with Pattinson for The New Yorker: "Whatever, we were young and stupid and, not to say that we made it so much better, but that’s what it needed, and that’s what anybody playing those parts needed to feel." (They dated from 2009-13.)

Pattinson's audition was also recalled by director Catherine Hardwicke on "The Big Hit Show" (h/t Entertainment Tonight):

"He walked in, his hair was dyed black for some play with these wacky bangs. He was a bit out of shape. His shirt was just all messy, and I'm like, 'Ehh, OK.' ... Rob and Kristen auditioned on my bed, the kissing scene, and Rob was so into it, he fell off the bed. I'm like, 'Dude, calm down.' I'm in there filming with my little video camera. And at the end, Kristen was like, 'It has to be Rob!'" 

Watch Pattinson's full GQ breakdown of his past memorable roles below.