Second seed Rafael Nadal came through a tough test against Diego Schwartzman to set up a last-four meeting with Matteo Berrettini, who overcame Gael Monfils in a five-set thriller.
Teenager Bianca Andreescu is also in the semi-finals on her main draw debut after beating Elise Mertens in three, and she will play Belinda Bencic, who edged past her close friend Donna Vekic.
Here the PA news agency looks back at day 10 and ahead to day 11 at the US Open.
Shot of the day
Monfils left nothing on the court as he bowed out against Berrettini.
Stat of the day
The eight semi-finalists in the men's and women's draws boast 41 grand slam titles between them. Serena Williams has 23, the other 18 belong to Nadal.
Match of the day
Probably the match of the tournament. Berrettini needed five match points to get past Monfils in an epic five-set marathon which went to a tie-break in the fifth.
(Love) Match of the day II
Monfils' girlfriend Elina Svitolina went through the wringer, which can't have been ideal preparation for her semi-final against Serena Williams.
Quote of the day
Brit watch
Jamie Murray and Neal Skupski beat American duo Jackson Withrow and Jack Sock to reach the semi-finals of the men's doubles. Murray then teamed up with American Bethanie Mattek-Sands and beat Rajeev Ram and Samantha Stosur to make the mixed doubles final as they bid to defend the title they won last year.
Fallen seeds:
Men: Gael Monfils (13), Diego Schwartzman (20)
Women: Donna Vekic (23), Elise Mertens (25)
Order of play
Arthur Ashe Stadium: (0000 BST)
Serena Williams v Elina Svitolina
Belinda Bencic v Bianca Andreescu
