AceShowbiz - Actor Colin Firth struggled with his gay role in upcoming movie "A Single Man" - because he couldn't resist kissing Julianne Moore. The Brit plays a homosexual college professor in Tom Ford's directorial debut opposite Moore, who stars as his character's lovestruck best friend.

But Ford had to berate Firth over one smooching scene, because the actor was so enamored with Moore he got carried away and couldn't stop kissing her. He says, "It never occurred to me that there was any issue about playing gay until Julianne kissed me and I had to resist."

"Julianne made that moment very difficult as I wasn't supposed to enjoy it. That was the one moment when Tom Ford had to get on my case. He said, 'You're supposed to be a gay man! Keep your hands to yourself and get your tongue out of her face!' "