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US OPEN

Caroline Wozniacki outlasts Maria Sharapova to advance

Caroline Wozniacki revels in the moment after upsetting Maria Sharapova at the US Open on Sunday. (John G. Mabanglo/EPA)

JOHN G. MABANGLO/EPA

Caroline Wozniacki revels in the moment after upsetting Maria Sharapova at the US Open on Sunday.

NEW YORK — Caroline Wozniacki trusts her stamina so much that she plans to return to New York in two months to run a marathon.

Maria Sharapova, usually the one wearing down opponents in the third set, sure couldn’t keep up on a steamy Sunday at the US Open. Wozniacki won, 6-4, 2-6, 6-2, in 2 hours, 37 minutes to get back to her first Grand Slam quarterfinal in more than two years — and get back in the headlines for reasons other than her personal life.

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‘‘The season for me has been a little bit up and down,’’ she said in quite an understatement, ‘‘and it’s so nice to kind of start feeling like I'm playing the way I want to.’’

Because of the heat, the players received a 10-minute break before the final set; Sharapova returned to the court late, arguing with the chair umpire after receiving a time violation warning. Perhaps sensing that she was fresher than the five-time major champion, Wozniacki later complained that Sharapova was dawdling between points.

Sharapova’s tardiness seemed to swing the Arthur Ashe Stadium crowd’s support squarely in Wozniacki’s favor. When the 10th-seeded Dane broke Sharapova to go up, 3-1, in the final set, she got a standing ovation from the fans and waved her arms to egg them on. Sharapova had appeared to hit a winner three times on that game’s final point only for Wozniacki to somehow chase down the ball. Finally, Sharapova hit a volley into the net.

Wozniacki’s defensive style is faulted as the reason that the former top-ranked player has made only one major final. She mixed in just enough aggression in the final set Sunday to keep the pressure on Sharapova.

‘‘She’s very good at getting a lot of balls back and making you hit another one,’’ Sharapova said. ‘‘In the end, I went for a little too much.’’

She insisted the conditions didn’t bother her. Sharapova had been 17-6 in three-set matches this year, including her come-from-behind second-round victory here.

The loss by the fifth-seeded Sharapova leaves No. 1 Serena Williams as the only woman remaining of the top six.

After a sloppy first set with 21 unforced errors, Sharapova was painting the lines in the second. Wozniacki seemed to spend most of the set watching in dismay as one of Sharapova’s 22 winners whizzed by.

Wozniacki said she told herself before the third set to go for her shots.

‘‘If I'm going to lose,’’ she recalled thinking, ‘‘at least I'm going to do it with dignity.’’

She closed out the match by breaking Sharapova’s serve again with a backhand winner. About a half-hour later, play was halted at Flushing Meadows because of thunderstorms with second-seeded Roger Federer among the players on the court. Matches resumed after a delay of about two hours.

Federer regrouped after the fortuitously timed delay to move on in four sets over Marcel Granollers. When they returned to the court following the interruption, Granollers won the first set. But Federer dominated the rest of the way in a 4-6, 6-1, 6-1, 6-1 victory.

Drenched with sweat on a humid night, Federer acknowledged afterward that the break helped him. He started serving better in the final three sets.

‘‘He was doing a lot of things really well,’’ Federer said later. ‘‘It was just, for me, going to be one of those things to like weather the storm and see if he could maintain that level of play or not and if I could lift my game up and see how that matched up. I think overall it worked out great at the end.’’

The 42d-ranked Granollers was looking to make the fourth round at the US Open for the second straight year.

Federer next faces Roberto Bautista Agut of Spain, who beat Adrian Mannarino, 7-5, 6-2, 6-3. The 17-time Grand Slam champion has dropped one set through three matches.

‘'I feel very explosive, quick,’’ Federer said.

Dominic Thiem, 20, made his first Grand Slam round of 16 with a 6-4, 6-2, 6-3 win over 19th-seeded Feliciano Lopez. Another first was achieved in the women’s draw by Peng Shuai, who had never been to a major quarterfinal before beating 14th-seeded Lucie Safarova, 6-3, 6-4.

Peng had been 0-5 in fourth-round matches at major tournaments. She becomes the third Chinese player to reach a Grand Slam quarterfinal after Li Na and Jie Zheng.

Safarova was coming off a semifinal run at Wimbledon.

Peng faced only one break point and had just seven unforced errors.

With mentor Martina Hingis cheering from the stands, 17-year-old Belinda Bencic became the youngest US Open quarterfinalist since Hingis herself in 1997.

Playing on Arthur Ashe Stadium, ninth-seeded Jelena Jankovic was far more rattled than an opponent 12 years her junior as Bencic won, 7-6 (8-6), 6-3.

Bencic saved three set points in the first, as Jankovic twice failed to serve out the set. She is the youngest player to reach a Grand Slam quarterfinal since Nicole Vaidisova at the 2006 French Open.

Hingis was 16 when she won the US Open in 1997 — Bencic was 6 months old at the time. Hingis’s mother, Melanie Molitor, coaches Bencic.

The 58th-ranked Swiss teen has now defeated top-10 players in consecutive matches after upsetting sixth-seeded Angelique Kerber in the third round.

Wozniacki will next face 13th-seeded Sara Errani, who ended the run of 32-year-old qualifier Mirjana Lucic-Baroni with a 6-3, 2-6, 6-0 victory.

Errani used consistent shots and a notoriously soft serve to end the tournament’s most unlikely comeback story.

Errani, the 2012 French Open runner-up, was content to play counterpuncher to the big-hitting Lucic-Baroni, who racked up 69 unforced errors. Errani made nearly 90 percent of her first serves, which averaged a mere 76 miles per hour.

The 121st-ranked Lucic-Baroni upset second-seeded Simona Halep in the third round. She is a former teen prodigy who last made a deep run in a Grand Slam tournament in 1999, when she reached the semifinals at Wimbledon.

As a 19-year-old, Wozniacki made the 2009 US Open final, losing to Kim Clijsters, and reached No. 1 in the world the next year. But she hadn’t been back to a Grand Slam quarterfinal since the 2012 Australian Open.

In the meantime, she was best known for getting engaged to star golfer Rory McIlroy — then getting dumped in late May after wedding invitations had gone out.

Wozniacki lost in the first round at the French Open soon thereafter and was upset in the fourth round at Wimbledon. She had been playing much better since, though, winning her first title in nine months at Istanbul then dropping a pair of three-set matches to Williams.

Meanwhile, Wozniacki announced a month ago that she planned to run the New York City Marathon on Nov. 2, somehow squeezing in training during a busy fall season.

‘‘Kind of clears my head,’’ she said of the extra running. ‘‘I feel more free when I go on court.’’

Wozniacki plans to stick around New York after the US Open to attend Fashion Week — including her pal Williams’s show — and get in some running in Central Park. The marathon prep has gone on hiatus the last few days, though.

As Wozniacki deadpanned, ‘‘I have a pretty big tournament here that I kind of want to try and win.’’

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