Matt Damon was thinking about his Bourne legacy.

The Air actor recently opened up about turning down the starring role in James Cameron's 2009 film Avatar despite an offer that included 10 percent of the box office back end that ultimately would have resulted in a $250 million payday. But as the Oscar winner admitted, he had a good reason for turning down the movie.

"I'm sure it's the most money an actor ever turned down, you know?" Matt revealed on the July 21 episode of Who's Talking to Chris Wallace. "But I had a contract."

At the time, he was starring as the amnesiac spy Jason Bourne in the action franchise. 

"I was in the middle of shooting the Bourne movie and I knew that we were going to need work at the end and I had to get it all the way to the finish line and I would have to leave the movie kind of early and leave them in the lurch a little bit," The Departed star told Chris Wallace. "I desperately wanted to work with Cameron. I mean, because he worked so rarely."

But despite the appeal, Matt couldn't see himself leaving his co-workers to finish the film without him. He added, "I don't know how I could have left all my friends in the lurch. You know what I mean?"

Ultimately, following Matt passing on Avatar due to his other franchise commitments, Sam Worthington assumed the leading role of Jake Sully.  

But while he's at peace with his decision to continue with his Bourne duties, Matt did share one friend's reaction to learning he could have played the Marine veteran turned Na'vi.

"I told John Krasinski, we were writing this little movie a long time ago called Promised Land and we were in my kitchen and it was a Saturday morning and we were on a break and I tell him about Avatar and he launches himself out of the chair," Matt recounted. "He starts pacing the kitchen, he goes, ‘Nothing in your life would be different today if you had done that movie, except you and I would be having this conversation in space."

Meanwhile, James has since laughed off Matt's decision to not take him up on the offer to star in the 2009 hit.

"He's beating himself up over this," he told the BBC ahead of the premiere of the sequel Avatar: The Way of Water in December. "And I really think you know, ‘Matt you're kind of like one of the biggest movie stars in the world, get over it.' But he had to do another Bourne film which was on his runway and there was nothing we could do about that. So he had to regretfully decline."

But with three films to go in the Avatar franchise, is there is there a chance viewers will get to see Matt appear on Pandora in the future?

"Must do it," the Titanic director said. "We have to do it so the world is in equilibrium again. But he doesn't get 10 percent, f--k that."