Who Is Chris Hemsworth?

'Thor' star Chris Hemsworth has been receiving rave reviews for his performance as the legendary Marvel Comics superhero in the big screen adaptation (out Friday).

Turns out, the Australian-born actor, 27, wasn't even on the director's original shortlist -- his younger brother Liam Hemsworth was.

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After months of searching for his star, director Kenneth Branagh narrowed his list to four actors, with each candidate invited to do a screen test, including Liam, 21, whose credits include the Miley Cyrus movie The Last Song and the upcoming adaptation of 'The Hunger Games.'

Today, Chris laughs about it, telling The Hollywood Reporter he wasn't in top form when he first met Branagh.

Branagh ultimately went back to the drawing board and decided to re-evaluate some previous contenders, like Chris.

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Liam was able to give his sib tips based on his own experiences auditioning. "We're competitive," Chris tells the Hollywood Reporter, "but in the best

way."

Chris also was given a boost by producer Joss Whedon (with whom he worked on the 2011 chiller 'Cabin in the Woods'), who placed a supportive phone call on the actor's behalf. A video the actor made with his mother also played helped.

"I was on the 17th floor of a hotel in Vancouver with my mom reading the lines to me," Chris tells The Hollywood Reporter. "And something great must have happened. It got me back in the room."

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Ultimately, Chris impressed not just Branagh but also Marvel Studios.

"We did two or three interview sessions before we tested him," Branagh tells The Hollywood Reporter. "We pretty much knew as we were shooting the test that he was the guy. It seemed, across these meetings, he had grown into it. He understood it better. And crucially, he was at ease."

After landing Thor role, Chris - whose major screen credits until that point included playing James T. Kirk's father, George Kirk, in the opening scenes of J. J. Abrams' 2009 'Star Trek' immediately started looking at the

comic books.

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He told The Los Angeles Times he noticed how the character "is 500 pounds or something and looks like Schwarzenegger. And I thought, OK, I'm not gonna get to that.' But I have to get bigger."

The filmmakers kept telling him to "'get as big as you can,'" recalled the actor (who is married to Spanish actress Elsa Pataky). "And then I came back right before Christmas, just before we started the movie, and had a final

sort of camera test and put the costume on and within a couple of minutes, my hands started going numb. And everyone was like, 'Yeah, that's not cool.' And I started getting pins and needles and you'd touch the skin and the blood wouldn't return to that area so quick. And I thought, 'OK, it doesn't fit.' "

The actor's costume ended up getting altered, and director Branagh instructed him to "pull back" on the intense workouts, he said.

Now, with Thor being his major introduction to American audiences, Chris - who was just named "Male Star of Tomorrow" at CinemaCon - stands to experience a career explosion.

He'll be reprising his Thor role in the 2012 ensemble adventure 'The Avengers' and has other projects in the can, including a 'Red Dawn' remake (he steps into the role originated by Patrick Swayze in the 1984 original) and 'Cabin in the Woods.'

"It's the normal sort of anxiety that you want it to succeed and do well," Chris told The Los Angeles Times. "So far, everything is in our favor."

See a clip from 'Thor':