NEW YORK (AP) — The latest on the U.S. Open (all times local):

7 p.m.

American Jack Sock, who retired because of heat illness while up two sets to one in his second-round U.S. Open match Thursday against Ruben Bemelmans, didn't hold a news conference and instead issued a statement.

"Playing in the U.S. Open is the biggest and most important moment of the season for me, so having to retire from my match today is extremely disappointing," the statement said. "I want to thank everyone for their support and can't wait to be back next year. I feel better already and look forward to playing Davis Cup."

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6:35 p.m.

Andy Murray rallied from down two sets to win his second-round match at the U.S. Open.

The third-seeded Murray beat 35th-ranked Adrian Mannarino 5-7, 4-6, 6-1, 6-3, 6-1 on Thursday, dominating the last three sets.

Murray is 35-1 in Grand Slam second-round matches, with the only loss coming in his U.S. Open debut a decade ago.

It was the eighth time in his career Murray came back to win from two sets down.

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5:50 p.m.

American Donald Young came from behind again, though this deficit wasn't quite as daunting.

Young dropped the first set Thursday before rallying to beat Britain's Aljaz Bedene 3-6, 6-4, 6-4, 6-2 at the U.S. Open. He advances to his first Grand Slam third round since last year's French Open.

On Tuesday, the 68th-ranked Young fell behind by two sets and a break against 11th-seeded Gilles Simon before roaring back for the five-set victory.

Young had 18 unforced errors in the first set Thursday against the 57th-ranked Bedene, who has never been past the second round at a major. But Young looked sharper and sharper as the match wore on and broke Bedene's serve eight times in the final three sets.

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5:30 p.m.

American John Isner keeps getting off the court quickly, a good thing considering the steamy weather early at the U.S. Open.

The 13th-seeded Isner's two matches have totaled 3 hours, 24 minutes — less than a single five-setter could take. He beat Mikhail Youzhny 6-3, 6-4, 6-4 on Thursday to reach the third round at Flushing Meadows for the seventh straight year.

Isner has held serve in all 83 of his games at the U.S. Open since the start of last year's tournament.

Isner had been 0-2 against Youzhny, though both of those losses were at least five years ago. The Russian is a former top-10 player, but his ranking is down to 93rd at age 33.

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5 p.m.

American qualifier Shelby Rogers has reached the third round at a Grand Slam tournament for the first time.

The 22-year-old Rogers beat Kurumi Nara of Japan 6-4, 6-4 at the U.S. Open on Thursday.

The 154th-ranked Rogers is playing in her ninth career major. She next faces second-seeded Simona Halep.

Nara, ranked 82nd, had upset 27th-seeded Alize Cornet in the first round.

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3:30 p.m.

Stan Wawrinka is a two-time major champion. Chung Hyeon is a 19-year-old playing in his second Grand Slam tournament.

That experience gap showed in what was a tightly contested match Thursday at the U.S. Open, which Wawrinka still pulled out in straight sets.

The fifth-seeded Wawrinka won 136 points to Chung's 125. The difference was the tiebreakers in a 7-6 (2), 7-6 (4), 7-6 (6) second-round victory. The three sets still took more than 3 hours.

Wawrinka had 26 aces and a total of 62 winners but a whopping 66 unforced errors against the 69th-ranked South Korean.

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3:25 p.m.

American Jack Sock was overcome by the heat and had to retire in the fourth set of his U.S. Open match.

The 28th-seeded Sock was three games from winning the match in the third set against Ruben Bemelmans on a hot, humid afternoon Wednesday. He received treatment after dropping the set, but in the third game of the fourth, he froze in place after a serve, unable to move his leg.

A trainer had to help him sit down on the court, and Sock was barely able to lift his arm to shake Bemelmans' hand when the Belgian walked around the net and over to him.

Trainers rubbed bags of ice on Sock's legs and neck. A wheelchair was brought out, but he was able to limp off with significant help.

It had been a breakthrough season for the 22-year-old Sock, who made his deepest run at a major by reaching the fourth round at the French Open and climbed to a career best in the rankings.

The 107th-ranked Bemelmans advances to a Grand Slam third round for the first time.

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2:50 p.m.

Simona Halep is feeling more comfortable as the No. 2 seed at the U.S. Open.

A year ago, she arrived at Flushing Meadows seeded second at a major for the first time. She was pushed to three sets in her opening match then upset in the third round by a qualifier.

No such problems so far this time. Halep has dropped just nine games through two rounds. She beat qualifier Kateryna Bondarenko 6-3, 6-4 on Thursday.

Recalling what happened when she reached No. 2 in the world for the first time, Halep said in an on-court interview: "I lost my mind a little bit."

"I couldn't be focused for what I have to do," she added. "With experience now I'm much better. I feel I have much more confidence in myself. I'm stronger mentally — and physically."

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2:35 p.m.

Wimbledon runner-up Garbine Muguruza is out of the U.S. Open.

The ninth-seeded Spaniard was upset by qualifier Johanna Konta 7-6 (4), 6-7 (4), 6-2 in the second round Thursday. At 3 hours, 23 minutes, it was the U.S. Open's longest women's match since the tournament introduced tiebreakers in 1970.

Muguruza had made at least the fourth round at the year's first three majors, losing to Serena Williams in the Wimbledon title match.

Three of the four women who had reached Grand Slam finals in 2015 are already gone from the U.S. Open before the third round: Australian Open runner-up Maria Sharapova withdrew because of injury, and French Open runner-up Lucie Safarova was upset in the first round. The only one left is the woman who beat them all in those title matches, Williams.

With Muguruza's defeat, six of the top 10 seeds in the women's draw are out at Flushing Meadows.

Muguruza had lost her opening match at her next two tournaments after Wimbledon. The U.S. Open is the only major at which the 21-year-old Muguruza has failed to make at least the fourth round in her young career. She had never even won a match at Flushing Meadows before Tuesday.

Konta, a 24-year-old Brit ranked 97th in the world, is into the third round at a Grand Slam tournament for the first time. She is now on a 15-match winning streak after capturing titles at two lower-level events then advancing through U.S. Open qualifying.

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1:10 p.m.

Struggling with dizziness and shut out in the first set, 16th-seeded Sara Errani rallied to win her second-round match at the U.S. Open on Thursday.

The diminutive Italian took a medical timeout after dropping the first five games, complaining of dizziness. The soft-serving Errani was broken nine times but found a way to beat 18-year-old qualifier Jelena Ostapenko 0-6, 6-4, 6-3 in 2 hours on a hot, humid day.

Errani said she woke up not feeling well, blaming the powerful air conditioning of New York hotels.

But the 2012 French Open runner-up could rely on her experience against the 114th-ranked Latvian, who was playing in her first U.S. Open. Ostapenko was unable to hold serve once in the final set, getting broken in her final six service games.

Errani won a match despite getting "bageled" in a set for the second straight U.S. Open. She beat Venus Williams 6-0, 0-6, 7-6 (5) in the third round last year.