Novak Djokovic cruised past Germany's Jan-Lennard Struff 6-3 6-1 on Wednesday to reach a record-equalling eighth Western & Southern Open semi-final where he will face Spaniard Roberto Bautista Agut.
The semi-finals will be played on Friday, scheduled as the final day of the event after organisers joined other sporting events in suspending play on Thursday in protest against racial injustice.
World number one Djokovic took advantage of a series of errors by Struff to grab control of the match and closed out the 62-minute encounter with a love service break to extend his unbeaten run to 24 matches.
"It was great. I started a little bit tight in my opening couple of service games ... Ever since I made that break at the beginning of the first set, I never looked back," said Djokovic.
"I really played very aggressive whenever I had the chance and I was going for my shots."
With the win, Djokovic tied Jimmy Connors, Stefan Edberg, Roger Federer and Bill Talbert's semi-final totals at the ATP Masters 1000 event.
Earlier, Bautista Agut produced a stunning comeback to defeat third seed Daniil Medvedev 1-6 6-4 6-3 and reach his maiden semi-final in the event, which is being played at Flushing Meadows, New York instead of Cincinnati due to COVID-19.
Bautista Agut's chances of victory appeared distant after the 24-year-old Russian cruised through the first set and had three break-point chances early in the second.
But the 32-year-old Bautista Agut began to play freer, charging the net and serving with more confidence.
"After the first set, I was thinking a lot of bad things," he said with a laugh. "I had to fight a lot in the second set. It was a really tough match."
In other quarter-final matches, Greek fourth seed Stefanos Tsitsipas advanced after Reilly Opelka, who was leading 6-5, retired due to a knee injury.
Tsitsipas will play Milos Raonic, a 4-6 7-6(2) 7-5 winner over Serbian Filip Krajinovic, for a spot in the final.
Raonic, a former world number three, said he considered not playing his quarter-final in solidarity with the protests over the police shooting of Jacob Blake, a Black man, in the city of Kenosha, Wisconsin, on Sunday.
The Canadian urged players and administrators to join hands and take a unified stand following Naomi Osaka's decision to pull out of her semi-final in protest over racial injustice.
"I think a bigger demonstration needs to happen and a bigger disturbance needs to happen," said Raonic, who was speaking before the tennis governing bodies jointly announced the postponement of Thursday's fixtures.
"I think it's about everybody being on the same page. If three guys, four guys step up tomorrow, but everything continues as normal on Monday when the U.S. Open starts, you know, have we taken that next small step after not playing the first day?"