Actors have to constantly turn down roles due to scheduling issues and prior committments, but it must hurt just a bit when they turn down a role in one of the top-grossing movies of all time. Matt Damon knows exactly what we're talking about, considering he turned down a role in 'Avatar.'

According to WENN, the actor was in talks with director James Cameron to star in the epic 2009 film, but there just wasn't enough time to take on the project between filming 'The Bourne Ultimatum' and 'The Green Zone.'

"I talked to Cameron and I read the script and I knew the movie was gonna be a big hit," Damon said. "I really wanted to do 'Avatar' and work with Jim Cameron and watch him direct and learn a lot."

But in the end, the lack of time won out, he said. "We were finishing 'The Bourne Ultimatum,' and I couldn't leave. It was a scheduling issue."