The cast of Iron Man 3 continues to grow.

Jessica Chastain is in negotiations to join the Marvel Studios production, which will start shooting in five weeks in North Carolina with Shane Black in the director’s seat, The Hollywood Reporter has confirmed.

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Chastain is not a female lead but will play a supporting role. The female lead belongs to Gwyneth Paltrow, who plays Tony Stark/Iron Man’s long-suffering girlfriend Pepper Potts. Insiders say that Potts will be a beefed-up presence in the new movie.

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Guy Pearce and Ben Kingsley are the previously-reported newcomers to the franchise. They are in various stages of negotiations to join mainstays Robert Downey Jr. and Paltrow, plus Don Cheadle.

Chastain next voices a role in Madagascar 3: Europe’s Most Wanted, which opens June 8.