Venus Williams is known for many things: her four Olympic gold medals, her five Wimbledon championships and her close relationship with her equally impressive sister Serena. Yet many sports fans may not realize she was a dedicated advocate for pay equality in professional tennis. ESPN's new documentary "Venus Vs." hopes to change that. From 2005 to 2007, Williams tried to convince Wimbledon officials that women tennis champions deserved as much prize money as their male counterparts. She lobbied British Parliament, UNESCO and Fleet Street for financial parity before Wimbledon officials relented following Williams' op-ed piece in The London Times. In 2007, the female Wimbledon winner made just as much as the male -- and guess who won the appropriately titled Venus Rosewater Dish that very year.

Directed by Ava DuVernay ("Middle of Nowhere"), "Venus Vs." is the first installment of ESPN Film and espnW's "Nine for IX" series, featuring nine documentaries focusing on female athletes and directed by women. The series was inspired by the 40th anniversary of Title IX and will air every Tuesday at 8 p.m. ET, starting July 2 with "Venus Vs." More information on this film as well as the other eight docs can be found on ESPN's Nine for IX website. Check out the trailer below: