Turns Out Venus Williams Is An Equal-Pay Trailblazer

At only 33-years-old, tennis superstar Venus Williams is known for being the ex-world No.1, a four-time Olympic gold medallist, and the less controversial counterpart to her younger sister Serena. On Tuesday night, a new documentary airing on ESPN hopes to add another punchy achievement her roster: equal pay advocate.

The new documentary, Venus Vs., reveals Williams' quiet struggle at the height of her tennis fame as an impassioned equal-pay activist. Turns out, she used her fame to convince Wimbledon to finally award male and female winners the same payment: $2.5 million.

Here's a preview:

The equal-pay debate in tennis is much larger-scale example of women being paid less for the same work. (For the record, women in America are still paid 77 cents to every man's dollar.) In tennis, men play five sets, while women play three—and women's matches tend to attract less ticket sales. Historically, tennis stars and sports personalities placed themselves firmly on either side of the fence, but Wimbledon winner Billie Jean King first drew awareness to the discrepancy when she brought home a third of what the male champion did in 1968.

Williams pointed out publicly that female tennis stars would be more than happy to play five sets rather than three, and began fiercely advocating for just that in 2005, at the height of the Williams sisters' glory.

"The message I like to convey to women and girls across the globe is that there is no glass ceiling," Williams said. "My fear is that Wimbledon is loudly and clearly sending the opposite message."

In 2007, Wimbledon conceded to her cause and began paying their winners equally; and the French Open swiftly followed its lead.

The documentary opens a nine-part ESPN series on women in sports named "Nine For IX," after the 40th anniversary of Title IX, the law amendment that outlawed sexual discrimination in any institution. You can watch it tonight at 8 PM, EST, or see more preview clips at the series' official site.