In the new drama Battle of the Sexes, recent Oscar winner Emma Stone plays tennis icon Billie Jean King, who famously challenged former champion Bobby Riggs (Steve Carell) to a match in 1973. And the project was fairly daunting for the actress, not least because it's her first role as a real person.

Emma Stone and Steve Carell in 'Battle of the Sexes'Emma Stone and Steve Carell in 'Battle of the Sexes'

"Billie Jean, in and of herself, was so inspiring," Stone says. "To get to play a person like her was a very fascinating and scary prospect. Luckily, she is also a pure force of nature and positivity."

Making the film offered Stone a chance to get to know King, but the actress was a bit reluctant about that. "I didn't talk to her too much while filming because it was too much pressure," she says. "And she has all the benefit of hindsight of decades older now."

To get into the role, Stone steeped herself in vintage TV footage. "We quickly learned that the choreography would be the most important thing," she says, "because learning how to do a serve or backhand like Billie Jean was more of an impossible dream than a reality! I really thought through the physicality. There was a lot of bulking up, tennis lessons, learning her stance and feeling my way into her body. She is a machine."

Sometimes this involved observing King closely while they were talking. "It was such a thing to figure out how her hands moved," Stone says, "and the way she moves within her body. I was a real creep. So now if we do an interview or we're sitting and talking, I find myself staring at her and watching how she's moving all the time, which I don't need to do any more. But that's how I relate to her. I'm like her creepy friend now!"

Just as fascinating to Stone was trying to capture King's outspoken attitude. "I was researching so much about her when she was around age 29, seeing how brave and daring she had to be, to speak out when it was not as open a forum as it is now."

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And Stone is a little frustrated that these issues are as timely now as they were back in 1973. "One of the great lessons that Billie Jean taught me is that you don't have to be perfect to be brave," she says. "This is a story that occurred 44 years ago, and this woman is an absolute icon of gender equality and LGBT rights. It is just amazing to show my generation, who didn't see the Battle of the Sexes, or maybe didn't know Billie Jean's whole story, how much she fought for change within her industry, which then affected larger change."