When Robert Pattinson** was cast as Edward Cullen in 2008's first Twilight film, the actor was under immense pressure to perform.

"It was terrifying," the leading man told E! News at the Nov. 12 premiere of the fifth and final film, The Twilight Saga: Breaking Dawn - Part 2. "I was shooting the last fight scene and I almost ripped my glute in the first shot I ever did. I was so nervous. I had to have a physio called in and have my butt cheek massaged for the rest of day. Very, very professional."

Luckily, the incident didn't sour the Twilight experience for the Englishman. In fact, Pattinson said "there could easily be another Twilight movie" in his future. "I wouldn't mind it all, to play a vampire again. It's quite a big genre."

For now, Pattinson is treating each moment of the Twilight tour as if it were his last. "You never really know what's going to happen," the 26-year-old said of the star-studded premiere. "It's a really nice energy. It's quite calm. It's not as crazy as it normally is. And everyone is quite appreciative. It's nice."

To prep for the premiere, Pattinson got his hair cut and traded his grungy duds for a Gucci suit. "I was looking like a mess," he laughed. "And also, when you put on a green houndstooth suit, you're like, 'I gotta do something!'"

Pattinson's only concern? "I had this terrible feeling driving here that Taylor** [Lautner**] was going to be wearing it as well!"

The Twilight Saga: Breaking Dawn -- Part 2 is in theaters Nov. 16.

This article originally appeared on Usmagazine.com: Why Robert Pattinson Needed His "Butt Cheek Massaged" on Twilight Set