The Wimbledon finalist’s defeat of Medvedev and Nadal’s subsequent exit has left Kyrgios as the title favourite at Flushing Meadows. He plays Russian Karen Khachanov on Wednesday (AEST) for a semi-final berth.
Fellow Australians and reigning Wimbledon champions Max Purcell and Matt Ebden also crashed out of the doubles with a 7-6 (7-5),3-6,6-3 loss to second seeds Neil Skupksi and Wesley Koolhof.
But Storm Sanders is through to the women’s doubles quarter-finals with American Caroline Dolehide after upsetting seventh seeds Zhaoxuan Yang and Yifan Xu 6-3,6-2.
Earlier,Jessica Pegula became the second American after Coco Gauff to move into the quarter-finals after the eighth seed beat Czech Republic’s Petra Kvitova 6-3,6-2.
Pegula,who will face top seed Iga Swiatek,is the highest-ranked American woman and the only player left in the top 10 in both singles and doubles.
She reeled off the last three games of the opening set,which ended with a double-fault by No. 21 Kvitova,and then the last six games of the fourth-round match after trailing 2-0 in the second set.
Thanasi Kokkinakis and Nick Kyrgios are out of the doubles competition.Credit:Getty Images
Swiatek was given a mighty scare by little-known Jule Niemeier before the Polish top seed finally handed the 108th-ranked German a 2-6,6-4,6-0 reality check.
The 21-year-old,who collected her second Roland Garros title amid a 37-match winning streak earlier this year,barely looked like the world’s best player as she sprayed the court with errors to surrender the opening set.
She handed Niemeier a break in the third game of the second set with a clumsy mistake at the net. Sitting on her bench with her towel over her head during the changeover,she loudly smacked her thigh in anger before returning to the court with new resolve,winning the next three games.
The pair traded breaks twice to close out the second set but Niemeier scarcely put up a fight in the third,producing 14 unforced errors as her game quickly unravelled.
Jessica Pegula after beating Petra Kvitova in the fourth round.Credit:Getty Images
Swiatek,who won in Doha,Indian Wells,Miami and Rome this year,sounded rattled after the match as her usual legion of Polish supporters rallied around her from the stands.
“I’m just proud that I didn’t lose hope,” she said in an on-court interview. “I had hard time like pushing her back.”
No. 24 seed Karolina Pliskova moved to the quarter-finals with a 7-5,6-7 (5),6-2 win over 26th-seeded Victoria Azarenka.
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Pliskova will face sixth-seeded Aryna Sabalenka,who bounced back from a slow start and visits from the trainer to beat No.19 seed Danielle Collins 3-6,6-3,6-2.
In the men’s draw,Russian Andrey Rublev downed British seventh seed Cameron Norrie 6-4,6-4,6-4 to move into the quarter-finals of a grand slam for the sixth time in his career.
The ninth-seeded Russian,who has never reached the semis at a major,will face Tiafoe.