Nearly men Zverev and Dimitrov target US Open semi-finals
US duo Taylor Fritz and Frances Tiafoe are standing in their way as they aim to end their country's 21-year wait for a male Slam champion.
In the women's draw, world number two Aryna Sabalenka, the runner-up in 2023, faces Olympic champion Zheng Qinwen while Emma Navarro takes on Paula Badosa in a clash between two women born in New York.
AFP Sport looks at Tuesday's four quarter-finals at Flushing Meadows:
Taylor Fritz (USA) v Alexander Zverev (GER)
Head-to-head: Zverev leads 5-4
Zverev was runner-up to Dominic Thiem in the 2020 US Open final where he gave up a two sets lead.
The German star also came off second-best to Carlos Alcaraz in the French Open final in June this year in another five-setter.
With four-time champion Novak Djokovic knocked out in the third round, the 27-year-old Zverev is the highest-ranked man left in his half of the draw as he seeks a third appearance in the semi-finals in New York.
"I'm doing everything I can to win a Slam, everything else is out of my power," he said.
"I'm trying my best and hopefully it will be enough at some stage in my career."
Fritz made the last eight in 2023 and has already reached three quarter-finals at the Slams this year.
Fritz defeated Zverev in the fourth round at Wimbledon in July from two sets down with the German hampered by a knee injury which forced him to complete the match "on one leg".
Grigor Dimitrov (BUL) v Frances Tiafoe (USA)
Head-to-head: Dimitrov leads 3-1
At 33, Dimitrov is the oldest man left in the draw and is seeking a second semi-final spot in New York after making the last four in 2019.
Back then, Dimitrov defeated Roger Federer in the last eight, ending the Swiss legend's US Open career before losing to Daniil Medvedev.
Widely regarded as one of the finest players never to win a Grand Slam title, Dimitrov has yet to even make a final at the majors after 15 years of trying.
Tiafoe, the tournament's great entertainer, is in the quarter-finals for a third successive year.
He made the semi-finals in 2022 where he lost in five sets to eventual champion Carlos Alcaraz.
Paula Badosa (ESP) v Emma Navarro (USA)
Head-to-head: Badosa leads 1-0
Badosa is in the last-eight in New York for the first time having never previously passed the second round.
The Spanish star, who was born in the city, has enjoyed a dramatic reversal of fortunes after being on the brink of retirement just three months ago due to a stress fracture of the back.
"I was feeling pain every day I was waking up. So for me, it didn't make sense," said Badosa of the injury which sent her world ranking plummeting out of the top 100.
Badosa is the first Spanish woman to make the quarter-finals since Carla Suarez Navarro in 2018 while it has been 28 years since a Spaniard last reached the semi-finals. That honour fell to Conchita Martinez.
Navarro made her first US Open quarter-final by knocking out defending champion Coco Gauff in three sets on Sunday.
Before this year, the 12th-ranked American had lost in the first round in her two previous visits.
Zheng Qinwen (CHN) v Aryna Sabalenka (BLR)
Head-to-head: Sabalenka leads 2-0
Olympic champion Zheng seeks to avenge her Australian Open final defeat to Sabalenka.
The Chinese star has made the quarter-finals for a second successive year after also losing to Sabalenka in 2023.
Zheng has already made history at this year's US Open by defeating Donna Vekic in the latest-ever finish for a women's match of 2:15 a.m. on Monday.
She is only the second Chinese woman to have reached two quarter-finals in New York after famed compatriot Li Na in 2009 and 2013.
Zheng has sent down a tournament-leading 49 aces over four rounds while the equally powerful Sabalenka has only dropped serve four times.
Sabalenka is in her fourth successive US Open quarter-final.