Andrea Riseborough felt "relieved and comfortable" when she found out she had a sex scene with her friend Emma Stone in 'Battle of the Sexes'.
The 36-year-old actress stars as Marilyn Barnett - the secret lover of then-closeted lesbian tennis legend Billie Jean King (Stone) - in the new film by Jonathan Dayton and admitted, despite the nature of the flick, there was no awkwardness on set.
Speaking to the Metro newspaper, Riseborough said: "People are always fascinated by that question. But no, it wasn't odd for me. Emma and I knew each other well enough to feel relieved and comfortable to be doing this with each other, which is not often something you find playing opposite someone romantically.
"What's more difficult is when you don't have great chemistry with someone - Emma and I have great chemistry. Or else if somebody is unprofessional or their ego is getting in the way or there is inappropriate behaviour."
The movie tells the story of the 1973 tennis match between King and Bobby Riggs (Steve Carell) which became the most-watched televised sports event of all time.
Trapped in the media glare, King and Riggs were on opposite sides of a binary argument, but off-court each was fighting more personal and complex battles.
King's husband was urging her to fight for equal pay, but she was also struggling to come to terms with her own sexuality while Riggs gambled his legacy and reputation in a bid to relive the glories of his past.
Riseborough - who has recently starred in 'Death of Stalin' - also admitted she never thought she'd get back into acting after taking a break from her big screen career.
She explained: "I really didn't think I would go back to acting this time. It was a case of being disillusioned with the industry because I had got slightly off track and started to make bigger studio films that weren't in line with anything that I believe in, so I felt a bit hopeless and a bit depressed. Now I just follow my instincts."