World No 1 Novak Djokovic defeated Kei Nishikori 6-7 (4/7), 6-3, 6-3, 6-2, taking his 17th consecutive victory over the Japanese star and improving to 18-2 in their overall rivalry.
“I was very pleased with the focus,” Djokovic said. “Maybe at some points I wasn’t my best, but I was determined and focused and that made the difference.”
With a fourth career US Open trophy, Djokovic is on course to complete the first men’s singles sweep of major titles in the same year since Rod Laver in 1969.
The imperious Serb marched toward a 21st career Grand Slam title, which would break the deadlock for the men’s record he shares with Rafael Nadal and Roger Federer, both absent with injuries.
He advances to a fourth-round matchup on Monday against 99th-ranked US wildcard Jenson Brooksby.
Tokyo Olympic champion Alexander Zverev defeated 184th-ranked Jack Sock 3-6, 6-2, 6-3, 2-1 when the American retired with a right thigh injury.
“I know I’m playing OK but a lot of other guys are playing well, too,” Zverev said. “I’m hoping to keep my form and give myself my best chance.”
Fourth seed Zverev, the 2020 US Open runner-up, joined qualifiers Oscar Otte and Peter Gojowczyk as the first German trio in the US Open fourth round since 1994 and any Slam last 16 since Wimbledon in 1997.
Wimbledon runner-up Matteo Barrettini, the Italian sixth seed, eliminated Ilya Ivashka of Belarus 6-7 (5/7), 6-2, 6-4, 2-6, 6-3. Next up is 144th-ranked Otte, who beat Italy’s Andreas Seppi 6-3, 6-4, 2-6, 7-5.