The 30-year-old actor – who put on 15lbs of muscle for the role – was thrilled with the special effects team’s efforts to make him look like the 90lb weakling his character Steve Rogers is at the beginning of the movie before becoming super-soldier Captain America because he didn’t want to use a body double.

Speaking at the film’s premiere at the El Capitan Theatre in Los Angeles on Tuesday, Chris said: “The beginning part of the movie is so crucial to get the audience invested in who Steve is, I didn't want to share that part of the performance with another actor, I talked to the director about it and thankfully, he agreed.

"It's pretty amazing. They took shape out of my jaw line, they shrunk my skeleton and they made my shoulders less broad."

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Chris - who walked the special blue and white carpet with co-star Hayley Atwell – admitted he was initially terrified to take on the role of the titular superhero in the big screen adaptation of the Marvel comic book series because he didn’t want to disappoint the die-hard fans.

The 30-year-old actor explained: “I was scared. If you are scared to do something you need to push yourself into it. If you push yourself in, it usually ends up being a good decision. Right now I am terrified."

A number of actors who will be appearing with Chris in ‘The Avengers’ movie attended the premiere, including ‘Iron-Man’ star Robert Downey Jr., ‘Thor’ actor Chris Hemsworth and Samuel L. Jackson, who plays super-spy Nick Fury.