Flavia Pennetta defeated Roberta Vinci in the final, 7–6(7–4), 6–2 to win the women's singles tennis title at the 2015 US Open.[1] It was her first and only major singles title, and she became the first woman to win her first major title after turning 30 years old. Pennetta was competing in her 49th major main draw, setting a new record for the most appearances in major main draws before reaching a final. This also marked Pennetta's last major appearance, as she retired from the sport at the end of the 2015 season.[2][3] Vinci became the first unseeded woman to reach a major final since Justine Henin at the 2010 Australian Open.[4] The final made Italy the fifth country in the Open Era to have two countrywomen contest a major final (after Australia, the United States, Belgium, and Russia). This also marked the first final with two first-time major finalists since the 2010 French Open.
Serena Williams was the three-time defending champion, but lost in the semifinals to Vinci. Williams was attempting to become the fourth woman (after Maureen Connolly, Margaret Court and Steffi Graf) to complete the Grand Slam. She was also attempting to win an Open Era record seventh US Open singles title. Williams' defeat to Vinci is regarded by some as one of the greatest upsets in tennis history.[5]