In tennis, the phrase "battle of the sexes" refers to certain matches held between professional male and female tennis players. These were highly publicized matchups that pitted often-overlooked female stars against slightly aged male ones.
The idea of a battle of the sexes in this manner was started by Bobby Riggs, a once-dominant male tennis player who retired in 1951. In 1973, Riggs declared he could beat any female player, under the notion that men were better at tennis than women.
Riggs first faced the women's world #1, Margaret Court. A 55-year-old Riggs defeated 30-year-old Court in two sets (6-2, 6-1) in front of a crowd of 5,000.
Riggs then faced 29-year-old Billie Jean King a few months later during the "Battle of the Sexes II," in front of over 30,000 people at the Houston Astrodome. The match was broadcast nationally and won by King in straight sets (6-4, 6-3, 6-3). This is the match most people associate with the "Battle of the Sexes" title.
Thirty years later, an anonymous source told ESPN that there were rumors of a fixing and/or interference of the match from the mafia, but there is no solid evidence to back this up. To this day, the battle of the sexes remains a landmark moment for the acceptance of women's tennis and women's sports in general.
King herself was a leader in the expansion of women's tennis. She used her power to demand the US Open Cup have equal male and female prizes and established what would become the Women's Tennis Association, among other off-court achievements.