Simona Halep's first-round loss toKaia Kanepi marked the first time in the Open Era that the top seed lost in the first round.[3] The losses of Halep in the first round and second seedCaroline Wozniacki in the second round marked the first time that the top two seeds failed to reach the third round, and the second time this happened at any major in the Open Era (following the2014 French Open).
Kathinka von Diechmann became the first player from Liechtenstein to qualify for the main draw of a major for the first time.
This marked the final major appearance for former world No. 2 and2015 WTA Finals championAgnieszka Radwańska, who lost in the first round toTatjana Maria. This also marked the first main-draw US Open appearance for future two-time championAryna Sabalenka, who reached the fourth round and was the only player in the tournament to win a set against Osaka.