Coco Gauff tearfully bowed out at the hands of defending champion Naomi Osaka.
Meanwhile, Rafael Nadal won in straight sets and set up a meeting with 2014 champ Marin Cilic.
Here PA looks back at day six, and forward to day seven, at the US Open.
Shot of the day
The doubles is in full swing, and so was Jamie Murray with this over-the-shoulder number.
Stat of the day
New York local Kristie Ahn, 27, is enjoying her home slam.
Well that was emosh
Osaka beat friend Gauff 6-3 6-0 and then consoled the 15-year-old afterwards.
Shock of the day
Seventh seed Kiki Bertens was dumped out in straight sets by Julia Goerges, who is seeded 26th.
Men: John Isner (14), Nick Kyrgios (28)
Women: Kiki Bertens (7), Caroline Wozniacki (19), Anett Kontaveit (21)
Order of play
Arthur Ashe Stadium:
Roger Federer v David Goffin
Serena Williams v Petra Martic
Elina Svitolina v Madison Keys
Novak Djokovic v Stan Wawrinka
Louis Armstrong Stadium:
Qiang Wang v Ashleigh Barty
Johanna Konta v Karolina Pliskova
Dominik Koepfer v Daniil Medvedev
Provided by Press Association Sport
Know more about Sport360 Application