Chris Evans has admitted he has nerves over playing famed superhero Captain America.
The Fantastic Four actor said he didn't immediately say yes to the role in Captain America: The First Avenger because of its implications.
"It wasn't an easy yes, I get nervous - Captain America means a lot of this," he told MTV.com.
"[Playing] Captain America just changes things, and there's really no off switch once you walk down that road."
Despite his initial doubts, the 29-year-old, who next appears with Michael Cera in Scott Pilgrim Vs The World, still considers it an opportunity of a lifetime.
"There's nothing wrong with the project," Chris explained.
"I love the people involved, the character, the script, Hugo [Weaving]. There was nothing wrong there, it was just about the lifestyle change and whether or not I was willing to do it."
The film, scheduled for release in 2011, also stars Hugo Weaving, Samuel L Jackson, Dominic Cooper and Hayley Atwell.