Billie Jean King New York City and Chicago with Kloss, her life partner. 18 finals (12 titles, 6 runner-ups) Singles Billie Jean King Billie Jean King ("née" Moffitt; born November 22, 1943) is an American former World No. 1 professional tennis player. King won 39 Grand Slam titles: 12 in singles, 16 in women's doubles, and 11 in mixed doubles. She won the singles title at the inaugural WTA Tour Championships. She often represented the United States in the Federation Cup and the Wightman Cup. She was a member of the victorious United States team in seven Federation Cups and nine Wightman Cups.
2015 US Open (tennis) 2015 US Open (tennis) The 2015 US Open was a tennis tournament played on outdoor hard courts. It was the 135th edition of the US Open, the fourth and final Grand Slam event of the year. It took place at the USTA Billie Jean King National Tennis Center. Marin Čilić was the defending champion in the men's singles event, but lost to eventual champion Novak Djokovic in the semifinals. Serena Williams was the three-time defending champion in the women's singles event and was also trying to complete the calendar Grand Slam, but she lost to Roberta Vinci in the semifinals.