LOS ANGELES (AP) -- At the back of a lavish Hollywood party where the Duke and Duchess of Cambridge are serving as the guests of honor, past the likes of Tom Hanks and Nicole Kidman, stands a tuxedoed and remarkably comfortable Chris Evans casually leaning against the bar, hair slicked back, champagne flute in hand.
Though he's been acting in films since he graduated from high school, Evans is among the youngest A-list attendees at the posh British Academy of Film and Television Arts soiree, one of the stops on the royal couple's recent trip to the U.S.
Yet wait, it seems Evans' coolness might be as much of a facade as his costume in "Captain America: The First Avenger."
"I just thought, `There's no chance these people will have any idea who I am,'" the 30-year-old actor remarked a week later during an interview to promote the live-action, 3-D rendition of the Marvel comic series.
It's hard to imagine that anyone, including British royalty, isn't aware of Evans, who's already played a Marvel superhero on the big screen: the wisecracking Human Torch in both "Fantastic Four" films.
The announcement that Evans would personify Captain America was met with both suspicion and excitement from fans. It's a feeling Evans understood.
The actor, perhaps better known for his hunky roles in mainstream ensembles like "Cellular" and "Not Another Teen Movie" than his nuanced performances in indies such as "Sunshine" and "London," is "more nervous than anything else" about the Friday debut of "Captain America."
The film, about a scrawny orphan named Steve Rogers who transforms into a chiseled supersoldier after being injected with a top-secret serum during World War II, is the final Marvel film before next year's fanboy-fantasy-come- true, "The Avengers."
"It's a double-edged sword," said Evans. "On one hand, it's terrifying, nerve-racking and intimidating. There's a swirl of negative emotions that arise. On the flip side, it's great. You have to maintain a healthy amount of respect. You have to understand this is where I want to be. It could be so much worse. My life has unfolded in a fortuitous fashion."
Evans, whose father is a dentist and mother is the artistic director of a youth theater in Concord, Mass., spent four months bulking up with a trainer in order to fill out Captain America's uniform. Computer-generated effects were used to shrink his body down for the scenes featuring Rogers before he became the Nazi-fighting peak of human perfection.
In the film, which is set mostly during World War II, Rogers is aided in the battle against an occult-obsessed Nazi commander nicknamed Red Skull (Hugo Weaving) by British agent Peggy Carter (Hayley Atwell), gadget whiz Howard Stark (Dominic Cooper), slick sidekick `Bucky' Barnes (Sebastian Stan) and overbearing Col. Chester Phillips (Tommy Lee Jones).
For his performance as the patriotic posterboy, Evans was inspired by a childhood friend named Charlie Morris "who always did the right thing." Instead of the snarky silliness that Evans memorably brought to the "Fantastic Four" movies, he instills Rogers with a subdued stoicism. In fact, Evans' casting compelled the screenwriters to craft less goofiness.
"We could dial back on the outright jokes in the script because he brings a likeability and warmth without having gag lines to punch it up," said screenwriter Christopher Markus. "In the beginning, when we were writing in a vacuum, we felt the pressure that he's getting too stiff. Give him a joke. Chris very wisely even took out a few of the wisecracks."
Evans hopes for "a long journey of character development" with Rogers, who will team up in the present day with Chris Hemsworth's Thor, Robert Downey Jr.'s Iron Man and Samuel L. Jackson's Nick Fury in "The Avengers" next year. The screenwriters also left gaps in his World War II exploits for "Captain America" sequels to flashback to in the future.
"We had to leave room in what we were telling for a career in World War II," said screenwriter Stephen McFeely. "When he comes back in the present day, he has to be a seasoned soldier and a legend. He can't be that having done just one battle. We knew that within the structure of whatever we're doing is that there had to be spaces where you could go."
Evans' reluctance to commit to not only "Captain America" but "The Avengers" and possible sequels — a superpowered endeavor that could last a decade — has been well documented. Evans felt another kind of pressure on set, too. He wasn't comfortable in the bulky Captain America costume until about halfway through the film's production in London last year.
"The first time I put the costume on, I was still apprehensive," said Evans, who has been filming "The Avengers" this summer in Albuquerque, N.M. "Then it just hits you. You're in it. You're in it now. Halfway through filming, it felt nice and comfortable. It's the source of the character. When you put the costume on, you can't help but feel heroic."
If the movie isn't as successful as "Iron Man" and "Thor," the blame could be placed on Evans, who will also be seen in theaters later this year as a drug-addicted lawyer in the drama "Puncture" and as the womanizing next-door neighbor of Anna Faris' character in the romantic comedy "What's Your Number?" It's not something he likes to think about right now.
"We overanalyze the past and we worry about the future," said Evans. "We don't spend enough time in the moment. I think doing that in this world, even if you have a six-picture deal with Marvel, you can get stuck in a pretty negative place. It's daunting, so you just say to yourself, `You know what? All I have to do is deal with today.'"
Derrik J. Lang can be reached at http://www.twitter.com/derrikjlang/.