Michael Douglas as Liberace and Matt Damon as Scott Thorson in "Behind The Candelabra" Credit: Claudette Barius/HBO

Michael Douglas has never shied away from doing explicit love scenes in movies. (Two words: Basic Instinct.) So when it came time to hit the sheets with Matt Damon for the upcoming HBO Liberace biopic, Behind the Candelabra, he threw himself completely into the role with no hesitation. (Damon plays the late pianist's live-in lover, Scott Thorson.)

"Once you get that first kiss in, you are comfortable," Douglas, 68, tells New York Magazine in a new interview. "Matt and I didn't rehearse the love scenes. We said, 'Well -- we've read the script, haven't we?'"

"The hardest thing about sex scenes is that everybody is a judge," he continues. "I don't know the last time you murdered somebody or blew anyone's brains out, but everyone has had sex and probably this morning, which means everyone has an opinion on how it should be done."

The fact that his partner in the scenes was Damon and not, say, Sharon Stone, was never an issue, the actor adds. "When I watch the movie, I forget it’s Matt and me pretty quickly," he says. "And soon after that, I forget it’s two guys. The fights, the love -- it’s a couple."

That said, there were a few boundaries Douglas wasn't comfortable pushing. "Liberace loved sex, and I didn't have a problem with that," he tells the mag. "But at one point, Steven Soderbergh wanted to show Lee watching a gay porno. I said, 'Steven -- you can't do this!' He said, 'It's HBO -- it's all right!' I said, 'It's not that: I'd like my kids to see this R-rated movie, but I don't want to show them a fourteen-inch d--k!'"

Douglas, married to Catherine Zeta-Jones, appears on the cover of New York Magazine's May 20 issue, where he rocks a bit of sparkly purple eyeshadow -- something he got used to during filming of the HBO film, set to air May 26. "I was the girl on this movie!" he tells the mag of Behind the Candelabra. "The hair and makeup for Liberace took two and a half hours. I've never done elaborate hair and makeup before. Up until now, my entire career has been contemporary."

Stepping outside of that comfort zone was liberating for the star, especially after his battle with stage-four throat cancer in 2011. "Cancer does give you a new rejuvenation," Douglas admits. "I know what it's like to be down. I lost a couple of good friends -- [actor] Larry Hagman and [singer-songwriter] Nick ­Ashford -- who had the same type of cancer that I did, and that makes you think. In the past, on purpose, I've never known what movie I'm going to do next. I never knew how I would feel when I finished a picture. Now it feels great to be back at work. Maybe that's the benefit of taking a break with cancer: Then, people say, 'What happened to him? Please come back.'"