<Tr> <Td> ← 2016 </Td> <Td> US Open </Td> <Td> 2018 → </Td> </Tr> <P> Angelique Kerber was the defending champion, but lost in the first round to Naomi Osaka . This loss would cause Kerber to fall outside the top ten in the WTA rankings for the first time since 2015 . </P> <P> Sloane Stephens won her first Grand Slam title, defeating Madison Keys in the final, 6--3, 6--0 . It was the first all - American women's final at the US Open since 2002, and the second time in three years that the final featured two first - time Grand Slam singles finalists from the same country . Stephens became the second unseeded woman in the Open era to win the US Open after Kim Clijsters in 2009 . </P> <P> For the first time since 1981 at the US Open--and at any Grand Slam event since the 1985 Wimbledon Championships--all four semifinalists were American . Both occasions were also the last time that four players from the same country accomplished these feats . In addition, Kaia Kanepi became the first qualifier to reach the US Open quarterfinals since Barbara Gerken, also in 1981 . </P>

Who won us open women's singles 2017