Her solution was to start a new women's tour — the Virginia Slims Circuit — much to Kramer's frustration.
The pay gap in tennis is much narrower today than in other sports and industries, and that's thanks to the women who took a risk in the 1970s and refused to play for less.
For example, the reaction to the test screening for the movie before the election was very different from the one after.
The directors still had a fair amount of work to do after the earlier screening, but they were still struck by how much more positive the feedback was after Trump was elected.
Neither watched, but both remember the era's sexual politics. "So things have gotten better." You can see that, for instance, in Howard Cosell's dated commentary during the match, which appears in the film from real, archival footage.
Faris recalls being taught in high school health class that homosexuality was a syndrome. "Here comes Billie Jean King — a very attractive young lady," Cosell said.
In real life, King handily beat the self-proclaimed chauvinist pig.
According to every poll, Clinton was about to do the same to another bombastic man with a habit of saying shocking things about women (among other demographic groups).
"I know he didn't think that women belonged in the booth, that's for damn sure," Casals recalled.
"I was doing my part — they wanted a battle of the sexes on and off the court." Dayton added: "We felt it was really important to put the real Howard Cosell in and use exactly what he said, because you almost wouldn't believe it otherwise. It's just a sign of where we were." Time can change our perspective, but it doesn't always take decades.
The movie is about more than the big match, and its other themes echo modern times, too.