Sam Rockwell is already on the set of Iron Man 2, filming the role of Justin Hammer, a rival industrialist to Robert Downey Jr.'s Tony Stark, but he wants fans to know that he won't be playing the white-haired, elderly Hammer from the comics. Rockwell spoke to MTV about his role in the film, where he described how his Justin Hammer would be different.

"They wanted to go with a rival for Tony Stark who is closer to his age, and make him American," Rockwell said. Rockwell went on to say that his character would serve as a rival in terms of influence, prestige and social power, but wouldn't be fighting against Tony Stark, decked out in his own suit of battle armor.

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"My character is the brains, not the brawn," Rockwell said.

Rockwell did suggest that the production has featured a great deal of improvisation and spontaneity amongst the Iron Man 2 cast, saying "There's a lot of improv." This suggests that director Jon Favreau is taking full advantage of his award-winning cast, and giving them room to bring many of their own acting choices to the characters - something that often results in more full-fleshed out film characters.

Iron Man 2, directed by Jon Favreau, will continue the tale of Tony Stark and his armored alter-ego as he continues his transformation from billionaire industrialist to super-hero. Robert Downey, Jr. will star as Tony Stark, with Paltrow returning in the role of his assistant Pepper Potts. Don Cheadle, Mickey Rourke, Sam Rockwell, Scarlett Johansson and Samuel L. Jackson also star. Iron Man 2 blasts into theatres May 7, 2010.