Michael Douglas was ''comfortable'' shooting love scenes with Matt Damon in 'Behind the Candelabra'.

The 68-year-old actor portrays late American pianist Liberace in the film which focuses on the musician's secret homosexual relationship with his chauffeur Scott Thorson - played by Damon - and although he was very nervous about their romantic scenes once they got the initial kiss out of the way everything was fine.

Douglas said: ''Once you get that first kiss in, you are comfortable. Matt and I didn't rehearse the love scene. We said, 'Well - we've read the script, haven't we?' The hardest thing about sex scenes is that everybody is a judge.''

Douglas was originally offered the role of Liberace in 2010 but had to put his career on hold after being diagnosed with stage four throat cancer later that year and he admits he was so weak from the illness he couldn't do anything other than rest.

Speaking to New York Magazine, he explained: ''When I was ill, I mostly lay on that couch. I watched a lot of sports, anything where I didn't know the ending ... I did [miss working], but I was too weak to miss much of anything. I was stage four, and there is no stage five.''

Although having cancer was the toughest period of his life, the Oscar-winning actor - who is married to Catherine Zeta-Jones, with whom he has two children, Carys, 10, and Dylan, 12 - insists he now has a new lease of life since beating the disease.

Speaking to Vulture magazine, he said: ''Cancer does give you a new rejuvenation. I know what it's like to be down ... Now it feels great to be back at work. Maybe that's the benefit of taking a break with cancer. Then people say, 'What's happened to him? Please come back.' ''

'Behind the Candelabra' is based on Scott Thorson's 1988 memoir and is scheduled to premiere on HBO on May 26.