Jessica Chastain (from “The Tree of Life”) may join Robert Downey Jr in “Iron Man 3”.

Shane Black (“Kiss Kiss Bang Bang”) is directing the film, due out 2013.

Chastain’s character would be “a sexy scientist every bit as smart as Tony Stark”, says Deadline.

Due to a clash with another movie, Chastain originally wasn’t going to be able to do “Iron Man 3” – and as such Marvel lined up meetings with possible replacements, Diane Kruger, Gemma Arterton and Isla Fisher – but seems they’ve now worked out that clash.

“Iron Man 3” stars Downey, Gwyneth Paltrow, Don Cheadle, and potentially Guy Pearce and Ben Kingsley – both up for villain parts.