Robert Pattinson suffered an embarrassing injury during the first day of shooting on his breakout hit,Twilight–the young star pulled a muscle in his butt.

The 22-year-old heartthrob damaged ligaments in his backside and had to undergo a butt-rub after he was given the task of lifting co-star Kristen Stewart into the air during their first scenes together.

Robert tells Britain’s Cosmopolitan Magazine, “I got injured on the first shot of my first day on Twilight. I lifted Kristen and ripped my arse cheek. I had to get a bum massage for the cheek.”