Alexander Zverev beat Borna Coric in four sets to reach his first US Open semi-final, where he will meet Pablo Carrena Busta who overcame Denis Shapovalov in five.
Naomi Osaka, the 2018 champion, cruised past Shelby Rogers and will take on Jennifer Brady, who beat Yulia Putintseva, in the last four.
Meanwhile Britain's Joe Salisbury and partner Rajeev Ram missed out on a place in the final of the men's doubles, going down in straight sets to Nikola Mektic and Wesley Koolhof.
Here, the PA news agency looks back at day nine at Flushing Meadows.
Picture of the day
Match of the day
Zverev v Coria may have been a tough watch but Carrena Busta and Shapovalov served up a late-night classic, the Spanish 20th seed winning 3-6 7-6 (5) 7-6 (4) 0-6 6-3.
Shot(s) of the day
Take your pick from a Brady masterclass.
Stat of the day
Zverev's win over Coric makes him the first German man to reach the US Open semi-finals since Boris Becker lost to Andre Agassi in 1995. In that same period, both Steffi Graf and Angelique Kerber have won the women's title.
Quote of the day
Quote of the day, part II
Quote of the day, part III
Former coach and current television analyst Brad Gilbert was put in his place early in the third set between Zverev and Coric. The German was distracted as he prepared to serve, turning to Gilbert, who was sitting close to court-side, and insisting: "You're talking too loud, man."
Threads of the day
Do not adjust your set.
Fallen seeds
Women: Yulia Putintseva (23).
Men: Denis Shapovalov (12), Borna Coric (27),
Up next
The remaining quarter-finals kick off with an all-mum battle between Serena Williams and the returning Tsvetana Pironkova, before Victoria Azarenka faces Elise Mertens of Belgium. In the men's event, Andrei Rublev plays third seed Daniil Medvedev, before second seed Dominic Thiem aims to live up to his billing against Australia's Alex de Minaur.
