World number one Daniil Medvedev wore down Denis Shapovalov 7-5, 7-5 to reach the quarter-finals of the Cincinnati Open on Thursday ahead of his US Open title defence.
The Russian top seed was joined in the last eight by Stefanos Tsitsipas, Felix Auger-Aliassime and Borna Coric but his compatriot Andrey Rublev, the sixth seed, was ousted by Taylor Fritz.
Third seed Carlos Alcaraz, a quarter-finalist at Flushing Meadows last year, beat former US Open champion Marin Cilic 7-6 (4),6-1 to set up a meeting with British world number 11 Cameron Norrie, who downed American Ben Shelton 6-0, 6-2.
Medvedev suffered a jarring early exit from the Canadian Masters last week but overcame some initial problems in a tricky tie against Shapovalov to edge both sets and book a meeting with American Fritz.
"In general, I managed to be pretty constant," said Medvedev.
"I got a lot of break opportunities. Broke first in the first set. Served pretty well even in the game where I lost my serve. In general, happy with my level and looking forward to the next matches."
Fritz had to fight back from a set down to beat Rublev 6-7 (4), 6-2, 7-5 on Center Court, finding his rhythm in the second set and pounding a dozen winners past the Russian to ensure he would continue his rise up the rankings.
"Obviously, I want to go even further, semis, finals, win the title but to put another Masters quarter-final on the record for the year helps a lot," said the Indian Wells champion, who stands on the brink of entering the top 10 for the first time.
Croatian Coric backed up his stunning victory over Rafa Nadal late on Wednesday by taking out another Spaniard in Roberto Bautista Agut.
Former World No 12 Coric is still on the comeback trail after shoulder surgery but showed he should not be underestimated at the US Open with a clinical 6-2, 6-3 victory.
A quarter-finalist at Flushing Meadows in 2020, Coric will next face Canadian seventh seed Auger-Aliassime, who saved two match points in the second set in a stunning 2-6, 7-6 (1) 6-1 comeback victory over Italian Jannick Sinner.
Greek fourth seed Tsitsipas took down Diego Schwartzman 6-3, 6-3 in a little over 90 minutes after the Argentine served up nine double faults and will next face American John Isner, a 7-6 (3), 1-6, 7-6(4) winner over compatriot Sebastian Korda.
Swiatek, Raducanu, Kontaveit ousted in Cincinnati
World number one Iga Swiatek and reigning US Open champion Emma Raducanu were both knocked out of the Cincinnati Open on Thursday, while second seed Anett Kontaveit also had her preparations for Flushing Meadows cut short in the round of 16.
Raducanu had beaten former Grand Slam champions Serena Williams and Victoria Azarenka in the previous two rounds but was brought down to earth with a bump in a 7-5, 6-4 loss to American seventh seed Jessica Pegula.
Another American, Madison Keys, earlier accounted for Swiatek to take her place in the quarter-finals and register her first win over a reigning world number one.
Swiatek saved four match points but was far from her best as she exited a second tournament in the North American swing at the last-16 stage after last week's Canadian Open.
Keys had failed to take a set off the Pole in two previous meetings but was far more clinical with her powerful returns and groundstrokes, breaking the world number one five times in the 6-3, 6-4 victory.
"I obviously had a couple of games with a couple of match points, but I'm just so happy to be able to get the win," said Keys, the 2019 Cincinnati champion.
"The last time I played her she beat me pretty badly, so I'm pretty glad to get that one under my belt."
Keys will next face Wimbledon champion Elena Rybakina, who beat Alison Riske-Amritraj 6-2, 6-4 to sail into the quarter-finals.
Wimbledon finalist and fifth seed Ons Jabeur also made her exit, ushered out of the door by twice major winner Petra Kvitova 6-1, 4-6, 6-0.
Kvitova next faces Australian Ajla Tomljanovic, who staged a stunning comeback to beat Russian Veronika Kudermetova 3-6, 7-6 (4), 6-3 and reach her first WTA 1000 quarter-final.
"The restaurant is still open and I'm going to get five Graeter's ice creams," said Tomljanovic, who was backing up after finishing her previous match at 1.30 a.m. local time on Thursday.
World number two Kontaveit looked to have taken charge of her tie against Zhang Shuai when she won the opening set at a canter but her Chinese opponent dug deep to claim a stunning 2-6, 6-4, 6-4 upset.
Eighth seed Aryna Sabalenka later takes on Shelby Rogers for a place in the last eight.