The director recently confirmed that production on the superhero sequel starring Robert Downey Jr. was at the halfway stage.
Speaking to Empire, he said: "Tony's expected to be a role model and I don't think he's ready to be one. He's under a great deal of pressure and when you're under pressure, I think you find outlets for that.
"That's one of the tensions of the film - it's one thing to say you're Iron Man, and another thing to actually become Iron Man."
He went on to tease that Stark's friend Jim Rhodes would be "stepping up in this film", adding: "Let me put it this way - Tony's not the only person with technology in the film."
Meanwhile, star Mickey Rourke has admitted that he is "having the time of my life" playing new villain Whiplash.
He explained: "It's been really brutal because my Iron Man suit weighs 23 lb. It's sort of a half-suit, with half my skin showing, with lots of Russian tattoos, because [Whiplash is just] out of a Russian-zone prison."
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