No. 3 seed Juan Martin del Potro continued his easy march through the U.S. Open, beating No. 20 Borna Coric 6-4, 6-3, 6-1 to reach the quarterfinals for the third year in a row.
The 2009 tournament champion has won all 12 sets he's played at Flushing Meadows so far in 2018.
Against Coric, del Potro produced 18 of his 33 winners with his powerful forehand.
The key came early, when del Potro broke in the last game of the opening set.
Defending champion Sloane Stephens returned to the U.S. Open quarterfinals with a 6-3, 6-3 victory over No. 15 seed Elise Mertens of Belgium.
No. 3 Stephens mixed her consistent, defense-to-offense style with the occasionally spectacular shot.
Now comes a rematch: She'll face No. 19 Anastasija Sevastova of Latvia, the same person she beat in last year's quarterfinals at Flushing Meadows.
Recalling that 2017 victory, decided by a third-set tiebreaker, Stephens said: "I had to dig really deep."
Sevastova advanced Sunday by eliminating No. 7 Elina Svitolina 6-3, 1-6, 6-0.
John Isner used a booming serve to reach the quarterfinals by beating Milos Raonic 3-6, 6-3, 6-4, 3-6, 6-2.
Isner, seeded 11th, also defeated Raonic at Wimbledon on the way to a semfinals appearance, his best finish in a Grand Slam. Isner is known for his marathon matches and played another long one in Louis Armstrong Stadium.
Isner had the crowd behind him on every point and the 6-foot-11 American pumped his fist on every winner. Isner improved to 5-1 lifetime against Raonic. Raonic needed treatment on his back after the fourth set.
The 33-year-old Isner is the tournament leader in aces and was nailing them against Raonic with 140 mph serves.
Serena Williams started fast and finished strong to reach the quarterfinals by beating Kaia Kanepi 6-0, 4-6, 6-3.
Williams, seeded 17th, won the first set in just 18 minutes. She quickly seized control again after dropping the second, racing to a 3-0 lead in the final set.
The six-time U.S. Open champion, who missed the tournament last year and gave birth to her daughter during it, advanced to face 2016 finalist and No. 8 seed Karolina Pliskova.
Kanepi, the 44th-ranked Estonian who knocked out top-ranked Simona Halep, was trying to make her second straight U.S. Open quarterfinal.
Karolina Pliskova reached the U.S. Open quarterfinals for the third consecutive year, beating No. 18 seed Ashleigh Barty 6-4, 6-4.
Pliskova was the runner-up at Flushing Meadows in 2016, when she beat Serena Williams in the semifinals. They could meet again this year in the quarters.
Against Barty, the eighth-seeded Pliskova won all 10 of her service games, saving 8 of 8 break points.
Rafael Nadal is back in the U.S. Open quarterfinals after beating Nikoloz Basilashvili 6-3, 6-3, 6-7 (6), 6-4.
The defending champion will next face No. 9 seed Dominic Thiem. That will be a rematch of Nadal's victory in the French Open final and will be their first meeting not on clay.
The top-ranked Spaniard improved to 8-2 in fourth-round matches in the U.S. Open, rebounding from dropping the tiebreaker in the third set Sunday to break the Georgian's serve twice in the fourth set.
Dominic Thiem has eliminated 2017 U.S. Open finalist Kevin Anderson with a 7-5, 6-2, 7-6 (2) victory in the fourth round.
Anderson was hoping to earn a rematch with Rafael Nadal, who beat him last year in the final at Flushing Meadows. The No. 5 seed had also reached the Wimbledon final this year.
Instead it's the ninth-seeded Thiem could play the top-ranked Nadal in the quarterfinals. That would be a rematch of this year's French Open final, won by Nadal.
Serena Williams felt she played her best match since her return to tennis while routing her sister in the last round.
She'll need to be sharp again, with Kaia Kanepi looking to knock out another women's tennis star.
Williams and Kanepi meet in a fourth-round match Sunday, when defending U.S. Open champions Rafael Nadal and Sloane Stephens also are in action.
Serena, seeded 17th, routed Venus 6-1, 6-2 Friday in matching the most-lopsided victory in the Williams sisters' series. That put her into the match against Kanepi, the 44th-ranked Estonian who upset top-ranked Simona Halep in the first round and is seeking her second consecutive quarterfinal in Flushing Meadows.
Nadal faces Nikoloz Basilashvili of Georgia and a victory for the top-ranked player could set up a quarterfinal matchup with No. 5 seed Kevin Anderson, whom he beat for last year's title.
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