Tom Cruise has insisted learning to sing for musical Rock of Ages was just like working out for an action movie - just using a different set of muscles.
Cruise attended the weekend premiere of the new film, directed by Hairspray's Adam Shankman, in London's Leicester Square, where fans flocked to meet him on the sparkling carpet shaped like a giant electric guitar.
"I applied the principles of how I learn anything. I started with the vocal coach and he just taught me the same way that preparing for a stunt, I work with the stunt team," Cruise said.
"I'm just learning how to move air through the body, 'cause really that's what singing is - developing those muscles.
"So I learned technically how to sing and then I really had to find that rock voice."
Cruise plays rock singer Stacee Jaxx in the film, based on the stage musical, alongside Russell Brand, Mary J Blige and Paul Giamatti, who also attended the premiere.
British comedian Brand lost his temper with revellers in the crowd who heckled him, shouting that he looked like "Jesus" and "a homeless person".
"I'd like to play Jesus, and wasn't he homeless for a while too?" Brand retorted.
The former drug addict admitted his role as a booze-swilling, hard-partying rocker in the film had reminded him of his past.
"When I was lying on the toilet floor I thought, 'Hello, here we are again ... on my own'."
He also revealed he gave his character a Brummie accent as a tribute to Black Sabbath rocker Ozzy Osbourne.
The film, released in cinemas on Friday, also stars Julianne Hough and Diego Boneta as the lead couple, and Malin Akerman as Cruise's love interest.