Meanwhile British number one Johanna Konta bowed out at the quarter-final stage.
Here, PA looks back at day nine and forward to day 10 at the US Open.
Shot of the day
Elina Svitolina ground down Britain's Johanna Konta, but came up with a few flashes of brilliance along the way including this vicious winner at the net.
Stat of the day
Serena Williams' 6-1 6-0, 44-minute take down of Wang Qiang was the quickest match at this year's tournament, and was also the American's 100th career victory at the US Open.
Shock of the day
After Novak Djokovic's exit, the scene was set for a final showdown between Roger Federer and Rafael Nadal. Grigor Dimitrov had other ideas.
Quote of the day
Men: Roger Federer (3), Stan Wawrinka (23)
Women: Johanna Konta (16), Wang Qiang (18)
Konta's fine run to the quarter-finals – her third in consecutive slams – was ended by Svitolina, 6-4 6-4 in an hour and 40 bludgeoning minutes. Jamie Murray and Neal Skupski are still in the men's doubles and face American duo Jackson Withrow and Jack Sock.
Order of play
Arthur Ashe Stadium:
Belinda Bencic v Donna Vekic
Matteo Berrettini v Gael Monfils
Bianca Andreescu v Elise Mertens
Diego Schwartzman v Rafael Nadal