Robert Pattinson has revealed that he suffered an embarrassing injury on the first day of shooting on Twilight - he sprained his "arse".

To make matters worse, the British star's buttock trauma came as he was lifting tiny co-star Kristen Stewart into the air during their initial scenes together.

"I got injured on the first shot of my first day on Twilight," he tells British Cosmopolitan.

"I lifted Kristen and ripped my arse cheek."

Rob was forced to take time out from filming, and had to undergo a butt-rub before he could continue shooting.

Or as he puts it, "I had to get a bum massage for the cheek."

Wonder who got that job?