Kristina Mladenovic vs. Roberta Vinci
Arthur Ashe Stadium, noon
A rare quarterfinal matchup of unseeded players starts the day off. Vinci, one of the top doubles players in the world the last three years, has done well in singles at the U.S. Open too, reaching the quarterfinals in three of the last four years. Mladenovic, a 22-year-old from France, has had more success in doubles in her young career so far, winning 12 WTA doubles titles and two Grand Slam titles in mixed doubles. But she has never reached a WTA singles final and is playing in her first Grand Slam singles quarterfinal.