Robert Pattinson almost "tore his arse-cheek" when shooting the first Twilight movie.

The actor is readying for the release of the final instalment of the vampire series, Breaking Dawn Part 2. He has reminisced about when he first won the role, which sees him playing brooding bloodsucker Edward Cullen.

Kristen Stewart portrays Edward's love interest Bella Swan, and one of Robert's first scenes was with her.

"On literally the first take of the first scene, I had to run over and pick up Kristen. And I almost tore my arse-cheek muscle, my glute, because I crouched down wrong. So I'd say, Don't squat down so low," he told Total Film, when asked what advice he'd give his younger self.

Robert has changed a great deal since the first movie hit screens in 2008. He was excited when he won the part and is still glad he was involved, but had no idea it would impact his life to such a big extent.

"I'm probably more insecure. My ego got smaller," he laughed, when asked how the franchise has changed him.

"I thought I was pretty cool after the first one. I finished the movie and for the first time I had some money So I spent eight months getting wasted with everyone thinking I was great. It was really fun. It was different at the start Becoming big now, you become insanely conservative. Terrified about everything. Now I just stay at home."

Robert and Kristen found love in real life, although earlier this year their romance was shaken when Kristen admitted having an affair. They are now understood to have reunited.