(CNN) For Emma Stone, living up to the legacy of the indomitable Billie Jean King in "Battle of the Sexes," about the infamous tennis match of the same name, was a big task to take on.

Not only was King a female athlete who had a major hand in paving the path for women who came after her in the sports world, but Stone physically had to look the part of a sun-kissed champion tennis player.

"It was the first time that I focused so, so much on the physicality of someone," Stone told CNN. "Playing an athlete, that is how she was able to make change in the world...that was her avenue to this voice that she had. So, that made physicality incredibly important."

Stone said the role called for her to get and look "stronger" -- something she found empowering.

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