On May 13, 1973, during the early years of the women’s liberation movement, tennis stars Bobby Riggs and Margaret Court face off in a $10,000 winner-take-all challenge match. The 55-year-old Riggs, a tennis champion from the late 1930s and '40s who was notoriously skeptical of women’s talents on the tennis court, branded the contest a “battle of the sexes.” The match, which was played on Mother’s Day and televised internationally, was held on Riggs’ home turf, the San Vincente Country Club in Ramona, California, northeast of San Diego. Proceeds were promised to the American Diabetes Association.

Bobby Riggs had originally proposed a male-female match-up to Billie Jean King, whom he dubbed the “leading women’s libber of tennis.” King ignored the offer, but Australian Margaret Court, who had won 89 of her last 92 matches and was the leading money-winner on the women’s professional tour, accepted. Leading up to the match, Riggs loudly and consistently belittled women’s tennis and its players to the media while Court, occupied with raising her one-year-old son, said little.

Court was a serve-and volley player, known for her tough play at the net. By contrast, Riggs was a baseliner, and it later became known that he had the court resurfaced to slow the game, giving him time to wind up and put more power into his stroke. The slow surface immediately put Court at a disadvantage. Riggs lobbed Court’s shots back to her, breaking the rhythm she was accustomed to on the hard-hitting women’s tour. Rattled, she lost the match, 6-2, 6-1.

The moment the match ended, Riggs again challenged Billie Jean King. She accepted, and their $100,000 winner-take-all match—dubbed by some “the libber vs. the lobber”—took place on September 20, 1973, in front of a sold-out Houston Astrodome crowd. The 29-year-old King prevailed, 6-4, 6-3, 6-3. At a news conference after the match, Riggs explained the loss: “She was too good, too fast. She returned all my passing shots and made great plays off them…I was trying to play my game, but I couldn’t.”

After Riggs’ death at age 77 in 1995, King complimented her former rival and his probably accidental contribution to the advancement of gender equality: “Our ‘Battle of the Sexes’ match helped to advance the game of tennis and women everywhere.”