In another universe, Jason Bourne or the Prince of Persia might have been running around the jungles of Pandora.

"Avatar" director James Cameron spoke to both Matt Damon and Jake Gyllenhaal  about playing the role of Jake Sully in the sci-fi epic that now stands as the biggest moneymaker in the history of Hollywood with $2.5 billion in worldwide box office.

Both stars, perhaps leery of a blue-in-the-face gig, declined, and the filmmaker instead went with his first choice -- unknown Aussie actor Sam Worthington, who was living in his car before he got the job. Cameron said he offered the role to the big-name stars only to placate the studio chiefs at Fox, who wanted a bankable star to offset some of the risks of the expensive project. 

 "I don’t think they ever had a problem with the CG, “ Cameron said. “Honestly, did I go out and try to woo them? No. I had my heart set on Sam. Maybe they sensed my lack of 100% commitment from me. Maybe it was the subject matter. This was a big 'Star Wars'-type movie. They’re both serious actors.”

Next up for those serious actors: Gyllenhaal stars in "Prince of Persia: The Sands of Time," based on the video game, which hits theaters in May, while Damon will be seen in "Green Zone" and is among the stars working on next year's "Happy Feet 2 in 3D."

-- Rachel Abramowitz

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Images: Matt Damon in 2007 in Berlin (Axel Schmidt  AFP/Getty Images). James Cameron goes native (Kevin Lingenfelser)