updated 03/23/2011 AT 8:00 AM ET
•originally published 03/27/2011 AT 12:55 PM ET
“I never thought I would get to kiss Michael Douglas,” Damon, who will play the boyfriend of Douglas’s Liberace, told PEOPLE Tuesday at the premiere of a different film, the documentary His Way, in Los Angeles.
“I kind of think of it in algebra terms, back to my high-school days,” added Damon. “It’s like the transitive property – by kissing Michael Douglas, I am making out with Catherine.”