Ben Affleck cast his brother Casey in "Gone Baby Gone" to make himself look "smart".

The "Smokin' Aces" actor gave his younger sibling a lead role in his directorial debut so he could take the credit when it shot him to stardom.

Ben, 35, said, "I cast him because I was lucky to get him. And I got to look smart. I got to be the guy who can say, 'I can show people how good he really is.'"