Larry W. King, the former husband of Billie Jean King who partnered with her on the creation of the WTA Tour and the “Battle of the Sexes” tennis match, died Friday.

He was 81.

King died at his home of prostate cancer, said his wife, Nancy Bolger King.

Larry King and Billie Jean King met at Cal State-Los Angeles and married in 1965. Billie Jean King credited him as “one of the unsung heroes in the establishment of women’s professional tennis in the early 1970s.”

“Larry’s intelligence, love, commitment and humor helped me navigate my career for more than 20 years,” Billie Jean King added in a statement, saying: “We were married for 22 years and in business together for decades. He was involved behind the scenes when the Original 9 signed our $1 contracts and he and I co-owned several tournaments on the Virginia Slims Tour.”

Together, Larry and Billie Jean King founded World TeamTennis, after Billie Jean was long interested in a team format for the sport. Larry King designed the colorful courts and revamped scoring system that helped popularize the sport.

He played a major role in a breakthrough for women’s tennis in 1973. The WTA Tour was formed that year, before King went on to beat Bobby Riggs in the “Battle of the Sexes,” which remains the most-watched tennis match in history.

Larry and Billie Jean King divorced in 1987. He later married Nancy Bolger King, whom he met on the women’s tour in the late 1980s. They moved a few years later to Grass Valley, where he co-founded Roller Hockey International, a professional roller hockey league played on inline skates; and Bridge Pro Tour, a professional bridge tour.

Besides his wife, King is survived by son Sky King and daughter Katie King, and their families.