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.

[2][3] Vinci was the first unseeded woman to reach a major final since Justine Henin at the 2010 Australian Open.

Williams was attempting to become the fourth woman (after Maureen Connolly, Margaret Court and Steffi Graf) to complete the Grand Slam.

Williams' defeat to Vinci is widely regarded as one of the biggest upsets in tennis history.

[5] This marked the major main draw debut of future Australian Open champion Sofia Kenin who lost to Mariana Duque Mariño in the first round.