Robert Downey Jr. has already starred in three "Iron Man" films and two "Avengers" blockbusters, but his next role may be his most controversial yet. When he appears in "Captain America: Civil War," his Tony Stark will be at odds with Cap -- but that doesn't make Stark a full-out villain, at least according to Downey. What's more, he considers his role in the film to be just as profound as another whole "Iron Man" film.

"In a way it's 'Cap 3,' but for me it's like my little 'Iron Man 4' and then it's back to the thing we all recognize," he told USA Today. "Everything pulls over to the side of the road when the thunder of an Avengers thing comes through because that's how it is until it changes. If it changes."

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As to whether or not Iron Man goes full villain in the "Captain America" sequel, he added, "If we're going to go there, then we've got to save it for my swan song. I would still like to keep a general audience and mildly be in their favor somehow."

Directed by Joe and Anthony Russo and starring Chris Evans, Robert Downey Jr., Scarlett Johansson, Anthony Mackie, Sebastian Stan and more, "Captain America: Civil War" opens on May 6, 2016.