In this Aug. 28, 2006 photo, Billie Jean King stands with her mother Betty Moffitt, center, and girlfriend Ilana Kloss, left. (Elise Amendola/AP)

Betty Moffitt, the mother of tennis great Billie Jean King and former major league pitcher Randy Moffitt, died Feb. 7 at her home in Prescott, Ariz. She was 91.

King’s publicist confirmed the death to the Associated Press. The cause was not disclosed.

King, who had been scheduled to attend the opening ceremony of the Sochi Winter Olympics in Russia with the U.S. delegation, announced that she would not make the trip to be at her mother’s side.

King described her mother as a good swimmer and dancer, who helped the tennis prodigy remain balanced with piano lessons and schoolwork.

Betty Jerman was born May 26, 1922, in Taft, Calif. She and her husband raised their two children in Long Beach, Calif., where they lived for more than 40 years. She was married for 65 years to Bill Moffitt before his death in 2006.

At King’s 60th birthday party in 2003 in Beverly Hills, Calif., the dance floor cleared when the couple twirled to Glenn Miller’s big-band era hit “In the Mood.”

Billie Jean King won 39 Grand Slam championships in tennis, including six Wimbledon singles titles in England from 1966 to 1975. She later became one of the first high-profile athletes to come out as gay. King said that her mother refused to discuss the matter at first but that eventually they reconciled and became close.

King’s younger brother, Randy Moffitt, pitched with the San Francisco Giants, Houston Astros and Toronto Blue Jays from 1972 to 1983.