Naomi Osaka became the first Japanese woman to reach the quarterfinals of a Grand Slam in 14 years, edging Aryna Sabalenka 6-3, 2-6, 6-4 in a matchup of 20-year-olds.
The No. 20 seed had to work much harder than she had so far in the tournament, where she had won 22 consecutive games leading into the match Monday.
She finally pulled it out when the No. 26-seeded Sabalenka double-faulted on match point, tossing her racket to the court in frustration.
The last Japanese woman to reach the final eight in a Grand Slam had been Shinobu Asagoe at the 2004 U.S. Open.
NEW YORK — Facing much more resistance from the 90 degree heat and 50 per cent humidity than his outclassed opponent, Novak Djokovic figures he can count on cooler conditions during a night match at the U.S. Open his next time out.
The next foe? That could be Roger Federer.
Djokovic left the court at Arthur Ashe Stadium for a medical timeout — the second time during the tournament he’s sought help from a doctor because of harsh weather — during what would become an otherwise straightforward 6-3, 6-4, 6-3 victory over 68th-ranked Joao Sousa of Portugal on Monday in the fourth round at Flushing Meadows.
"I’m not 21 anymore. That was 10 years ago. I still don’t feel old. But at the same time, there is a little biological clock that is not really working in your favour," the No. 6-seeded Djokovic told the crowd afterward. "Sometimes, you just have to survive."
He reached the quarterfinals for an 11th consecutive appearance in New York as he bids for a third U.S. Open championship and 14th Grand Slam trophy. To add to his resume, though, he might need to beat Federer, who has won five of his men’s-record 20 major titles at Flushing Meadows.
Federer was scheduled to play 55th-ranked John Millman of Australia in the fourth round on Monday night. Like Sousa, Millman had never before made it this far at a Slam.
The other quarterfinal on the bottom half of the draw will be 2014 runner-up Kei Nishikori against 2014 champion Marin Cilic or No. 10 David Goffin. Nishikori advanced in the afternoon with a 6-3, 6-2, 7-5 victory over Philipp Kohlschreiber.
Djokovic, who is coming off a title at Wimbledon, wasn’t at the U.S. Open a year ago, when he missed the last half of the season because of an injured right elbow that eventually was surgically repaired this February.
Asked whether he thought during that time away about returning to the height of his powers, Djokovic replied: "I have imagined. I have hoped for. I have prayed for that."
He improved to 28-0 at the U.S. Open against opponents ranked outside the top 50, and here’s another reason it wasn’t all that surprising the way things went Monday: Djokovic is now 5-0 against Sousa, taking all 14 sets they’ve played against each other.
The heat, though, is much tougher on Djokovic, who showed the same blank expression, rosy cheeks and sweat-soaked shirt as during his first-round match last week. That was the first time in tournament history that the U.S. Open created an extreme heat policy for men’s matches — they can opt for a 10-minute break between the third and fourth sets — similar to what’s standard on the women’s tour, when there can be a delay between the second and third sets.
Kei Nishikori is into the quarterfinals of his return to the U.S. Open.
The 2014 runner-up in Flushing Meadows beat Philipp Kohlschreiber 6-3, 6-2, 7-5 to reach the final eight in his second straight Grand Slam tournament.
Nishikori missed the U.S. Open last year because of a right wrist injury. The No. 21 seed from Japan returned to the tour early this year, building his confidence back with a victory in a Challenger Tour event, then reached the final in Monte Carlo and the quarterfinals at Wimbledon, where he lost to eventual champion Novak Djokovic.
He will next face either No. 7 seed Marin Cilic — who beat him in the 2014 U.S. Open final — or No. 10 David Goffin.
Kohlschreiber was denied again in his fifth attempt to win a fourth-round match at the U.S. Open. The German reached his lone Grand Slam quarterfinal at Wimbledon in 2012.
Madison Keys returned to the U.S. Open quarterfinals with a 6-1, 6-3 victory over No. 29 seed Dominika Cibulkova of Slovakia.
Keys was an Open finalist a year ago and lost to Sloane Stephens. She lost to Stephens again this year in the French Open semifinals.
The 14th-seeded Keys will play the winner of the Carla Suarez Navarro vs. Maria Sharapova match in the night session at Arthur Ashe Stadium.
Keys has reached at least the quarterfinals in three of the four Grand Slam tournaments this year. She had six aces and no double-faults Monday in perhaps her best performance of the tournament.
Lesia Tsurenko reached her first Grand Slam quarterfinal by outlasting teenager Marketa Vondrousova 6-7 (3), 7-5, 6-2 after feeling ill earlier in the match.
Tsurenko struggled in the heat. She took long pauses between points in the first-set tiebreaker, then left the court for treatment after it. She still and looked weary to start the second, leaning on her racket between points while falling behind 2-0. She said afterward she felt dizzy and was "just asking nature, I don’t know, the god, to move the shade."
She was able to play through the pain and eventually won the match in 2 hours, 32 minutes.
The Ukrainian got some help from her opponent. She hit only 17 winners but the 19-year-old Vondrousova made 90 errors — 73 unforced.