American tennis champion who won 37 Grand Slam titles
The American tennis champion Margaret Osborne duPont, who has died aged 94, amassed an astonishing total of 37 Grand Slam titles, in singles, doubles and mixed doubles. These included singles titles at Wimbledon in 1947, at the French Championships in 1946 and 1949, and at three consecutive US Championships (which were then played on grass at Forest Hills) between 1948 and 1950.
As a singles player, Osborne duPont was relentless in her pursuit of victory, frequently fighting off match points. Her longest duel came against Louise Brough in the 1948 US final, which she won 6-4, 4-6, 15-13. Ranked No 1 in the world from 1947 until 1950, she held a place in the US top 10 for 20 years without interruption between the ages of 20 and 40 and managed to win a Grand Slam title at 44 – the mixed doubles at Wimbledon with Neale Fraser in 1962.
Billie Jean King called Osborne duPont "one of my she-roes". Angela Mortimer Barrett, who won Wimbledon in 1961, remembers beating Osborne duPont in the mid-50s at Wimbledon. By then Osborne duPont had passed the peak of her playing career, but, Mortimer Barrett recalls: "It was still tough to beat her on a damp grass court because you had to find a way to hit up off a low bounce to make the pass as she chipped and chopped and came storming into the net. She was a very aggressive player."
Born Margaret Osborne on a ranch in Joseph, Oregon, she was an athletic child and played most sports, but took up tennis only at the age of nine when her parents moved to San Francisco. She was soon to be found hitting balls on the famous Golden Gate Park courts, where top-ranked Americans including Tappy Larsen and Whitney Reed learned the game. Tennis became an obsession and only the second world war, which saw her working in a munitions factory in Sausalito, just across the Golden Gate Bridge, interrupted her full playing schedule.
Even then she managed to start her extraordinary run of dominance in doubles at Forest Hills with Brough, winning the first of nine consecutive titles in 1942. The pair returned to winning ways in 1955, victorious three more times to set a record of 12 doubles titles at the US Championships which has not been bettered in the Open era. All told, the pair won 20 Grand Slam titles, a total which was eventually equalled by Martina Navratilova and Pam Shriver.
In 1947, Osborne married William duPont, heir to a chemical company fortune. As an avid fan of the game himself, he was extremely supportive of her tennis career but, suffering from breathing problems that were alleviated by living in California during the winter months, he insisted his wife stay with him, with the result that she never played in the Australian Championships.
She gave birth to a son, William, in 1952 and immediately resumed her tennis career, becoming one of the few players to win Grand Slam titles after having children. The duPonts divorced amicably in 1964 and, although she stayed in the east initially so that young William could be near his father, she did not linger when her ex-husband died a year later. Osborne duPont spent the rest of her life with Margaret Varner Bloss, a squash, badminton and tennis player herself. Although Osborne duPont won the vast majority of her doubles titles with Brough, she and Varner Bloss had reached the Wimbledon doubles final together in 1958, losing to the formidable pair of Althea Gibson and Maria Bueno.
Together they moved to a ranch near El Paso, Texas, Varner Bloss's home town, where they bred thoroughbred horses, giving them names such as Tennis Star. Osborne duPont continued to follow the game until the end and, reportedly, was particularly impressed with Andy Murray's spirited performances this summer. "The game has changed so much," she told the El Paso Times. "We played with wooden rackets. But for me it was just tennis, tennis, tennis. I'm not sure why I loved the game so much. But I did. I just did. And I always have."
She is survived by her son, four grandchildren and Varner Bloss.
• Margaret Evelyn Osborne duPont, tennis player, born 4 March 1918; died 24 October 2012