Serena Williams lost to unseeded Roberta Vinci in U.S. Open semifinals, thus ending her quest to become the first women’s singles player since Steffi Graf in 1988 to complete the calendar Grand Slam by winning the Australian Open, French Open, Wimbledon and the U.S. Open in the same year. Had she won, Williams also would have tied her with Graf for the second most career Grand Slam tournament wins and the most since the Open Era, which began in 1968 when professionals were allowed to compete in Grand Slam tournaments.