Margaret Osborne duPont, an all-American girl, dominated US and world tennis during the 1940s and 1950s, winning six Grand Slam singles and 31 doubles titles; she was among the most dominant doubles players of her era, and her doubles record ranked her all-time fourth, behind Margaret Court, Billie-Jean King and Martina Navratilova.
DuPont was a tour de force in the game, 156 weeks as the world's No 1, and featured in America's top five for 20 years, although she never played in the Australian Open. Her husband forbade it, believing it would be detrimental to his health.
She had style and panache on and off the court, and was admired for her tenacity, endurance, sportsmanship as well as desire to win: "I'm not sure why I loved the game so much. But I did. I just did. And I always have."
Her ability to handle pressure with poise, and her aggressive game, were visible when she clinched her first Grand Slam doubles title in the US Championships (US Open) in 1941, having lost the first set. She won a further 12 women's doubles crowns (10 in a row, 1941-50), nine mixed double and three singles titles at the US tournament: 25 titles, a record to this day. Her overseas victories included the 1947 singles title in 1947.
She was born Margaret Evelyn Osborne in the rural town of Joseph, Oregon, daughter of modest ranch owners. She showed natural athletic ability, horse-riding and playing baseball with her brother: "I could throw the ball like a boy." Because of her father's failing health, the family moved to Spokane, Washington where, at nine, she took up tennis. Two years later they moved to San Francisco where she played on public courts and competed in tournaments.
In 1936 duPont graduated from high school but was unable to fund further study, and so, aged 18, began a tennis career. She won the junior nationals singles and double titles in Philadelphia, then travelled the country. She trained for a year with the coach Tom Stow, who noted "a dazzling arsenal of shots, including low-flying spin volleys and gravity-defying lobs." During the Second World War she worked in a shipbuilding plant.
She met the tennis-loving William duPont Jr, heir to a chemical company fortune, and interrupted her career to marry in 1947, and again in 1952 for the birth of their son, Bill: she was one of the very few women successfully to juggle tennis with motherhood. The family lived at their Delaware estate, Bellevue Hall, where she could practise on nine tennis courts – grass, concrete and clay.
DuPont won six Grand Slam singles titles, saving match points in the finals of the 1946 French Open and in the 1948 US Championships, against her good friend Louise Brough. This match exemplified her physical endurance; it was the longest women's singles final ever played at the tournament (48 games); she won the last set 15-13. In the same tournament, she and Bill Talbert outlasted Gussie Moran and Bob Falkenberg in a 71-game, two day, mixed doubles semi-final, a record that stood for over 40 years. When she lost, it was rarely in straight sets.
Her most successful doubles partnership was with Brough. Together they held the record for most Grand Slam doubles titles, 20, until it was equalled in 1989. DuPont and Brough also had an unbeaten streak, from 1942 to 1950, and a monopoly on the US doubles crown, winning it in 12 out of 14 attempts. Her distinction as the oldest woman, at 44, to win a Wimbledon title, in 1962 with Neale Fraser, lasted until 2003. In 1962, duPont and Margaret Bloss defeated Britain in the Wightman Cup doubles; DuPont had an unblemished record, 19-0.
The duPonts divorced amicably in 1964 and she moved to Texas, where she shared a home with her former tennis partner Bloss. She was inducted into the International Tennis Hall of Fame in 1967 and had a "huge impact" on players such as Billie-Jean King, who said, "she was a great influence on my life … and her career wasn't just about winning matches, it was also about mentoring others."
DuPont continued to follow tennis: "Our game was more about finesse, not so much power as today." Because the stars of her day were not paid, they played "for the love of the game."
Margaret Osborne duPont, tennis player: born Joseph, Oregon, US 4 March 1918; married 1947 William DuPont Jr (divorced 1964; one son); died El Paso, Texas 24 October 2012.