Spanish second seed Alcaraz and Serbian legend Djokovic both booked their passage into the last 16 with comfortable victories and now stand just two wins away from meeting in the last four.

Alcaraz breezed past Italian 32nd seed Luciano Darderi in emphatic fashion, winning 6-2, 6-4, 6-0 on the Arthur Ashe Stadium while Djokovic, who is chasing a record 25th Grand Slam singles title, took care of Britain's Cam Norrie 6-4, 6-7 (4/7), 6-2, 6-3.

Alcaraz's one hour 44-minute victory sends the 2022 US Open champion into a meeting on Sunday against France's Arthur Rinderknech, who defeated compatriot Benjamin Bonzi 4-6, 6-3, 6-3, 6-2.

Alcaraz needed a medical timeout while leading 5-4 in the second set for treatment on his right knee, but later said he had no injury concerns.

- Djokovic milestone -

Djokovic, 38, meanwhile was clinical in his win over Norrie in the evening session, which sends him into a fourth round tie against German veteran Jan-Lennard Struff.

"Coming into any match you really want to win in straight sets without any drama but obviously that's not possible," said Djokovic after becoming the oldest man to reach the US Open last 16 since Jimmy Connors in 1991.

"It's good that I get tested," he added. "I'm still trying to find my rhythm and my groove on the court."

Djokovic's fourth round opponent Struff dealt a blow to American hopes of a first home US Open champion since 2003 with a 6-4, 6-3, 7-6 (9/7) defeat of popular 17th seed Frances Tiafoe.

"I don't know how to recover from this, to be honest with you," Tiafoe said. "I haven't been this down in a very, very long time."

Tiafoe's exit came after another disappointing loss for US fans, with big-serving Ben Shelton departing the Louis Armstrong Stadium in tears after being forced to retire after the fourth set of his match against French veteran Adrian Mannarino.

Shelton, 22, was leading 6-3, 3-6, 6-4 when he began to feel pain in his left shoulder. He played on but threw in the towel after Mannarino took the fourth set.

"I'm not a guy who would retire if I could continue," said a dejected Shelton.

With Shelton and Tiafoe exiting, it was left to last year's beaten US Open finalist Taylor Fritz to lift home hopes, and the fourth seed delivered in an evening victory over Swiss qualifier Jerome Kym, winning 7-6 (7/3), 6-7 (9/11), 6-4, 6-4.

- Sabalenka revenge -

In the women's draw, meanwhile, world number one and defending champion Sabalenka avenged her 2021 US Open semi-final defeat to Leylah Fernandez with a straight-sets victory over the Canadian 31st seed on Armstrong.

Sabalenka was left distraught after being upset by the unheralded Fernandez four years ago with a place in what would have been her first Grand Slam final there for the taking.

But the 27-year-old from Belarus made sure there was no repeat on Friday, seeing off Fernandez 6-3, 7-6 (7/2). Sabalenka's victory saw her extend her incredible winning streak in tie-breaks to 18.

"I wanted this revenge badly," Sabalenka said afterwards. "It was a tough lesson for me back then.

"I just wanted to prove to myself that the lesson was learned and that I developed as a player and I could get this win."

Sabalenka faces unseeded Spaniard Cristina Bucsa in the next round. Bucsa moved on Friday with an upset 3-6, 7-5, 6-3 win over Belgian 19th seed Elise Mertens.

There was another upset in the late game on Arthur Ashe, with Taylor Townsend bundling out Russian fifth seed Mirra Andreeva 7-5, 6-2.

Elsewhere, Kazakh ninth seed Elena Rybakina outclassed Britain's Emma Raducanu, winning 6-1, 6-2 to move into a last 16 tie against 2023 Wimbledon champion Marketa Vondrousova, a 7-6 (7/4), 6-1 victor over Italian seventh seed Jasmine Paolini.

In other women's draw matches, American fourth seed Jessica Pegula comfortably defeated Victoria Azarenka 6-1, 7-5 to reach the fourth round, where she will face compatriot Ann Li.