The Latest: Zverev vs. Mannarino starts after delay at Open 2:10 p.m.Naomi Osaka is headed to a third set in the U.S. Open’s third round.The two-time Grand Slam champion took the opening set 6-3, but 18-year-old Marta Kostyuk, who is playing in just her second major tournament, grabbed the second in a tiebreaker.When the second set ended with Osaka missing a backhand return, she flung her racket away.Osaka won the U.S. Open in 2018 and the Australian Open the following year. She has been ranked No. 1 and is seeded fourth at Flushing Meadows. Kostyuk is ranked 137th.___12:45 p.m.Petra Martic is the first player into the fourth round at this year’s U.S. Open.The No. 8-seeded Martic made it that far at Flushing Meadows for the second year in a row, advancing Friday with a 6-3, 6-3 victory over Varvara Gracheva. ___11:10 a.m.Play is underway in third-round matches on Day 5 at the U.S. Open.Past champions Naomi Osaka and Novak Djokovic are among those scheduled to play in Arthur Ashe Stadium later Friday.Osaka will face Marta Kostyuk to begin the day session in the tournament’s main arena. Naomi Osaka has moved into the fourth round of the U.S. Open by getting past 18-year-old Marta Kostyuk 6-3, 6-7 (4), 6-2.Osaka threw her racket after ceding the second set, then was one point from trailing 3-1 in the third.But she saved five break points to get to 2-all, starting a five-game run that ended the match.Osaka is a former No. 1-ranked player who has won two Grand Slam titles, including the 2018 U.S. Open.The 137th-ranked Kostyuk was appearing in only her second major tournament. Associated Press September 4, 2020 Caty McNally, an 18-year-old from Ohio, eliminated No. 21 seed Ekaterina Alexandrova in three sets in a rain-delayed match to reach the U.S. Open’s third round.McNally’s 4-6, 6-3, 7-6 (2) victory gives the host country 11 women in the third round at Flushing Meadows for the first time since 1992.The match was suspended Thursday because of the weather. McNally, who plays doubles with 16-year-old American Coco Gauff, had never been this far in singles at a Grand Slam tournament.___ Share This StoryFacebookTwitteremailPrintLinkedinRedditNEW YORK (AP) — The Latest on the U.S. Open tennis tournament (all times local):5:45 p.m.The third-round U.S. Open match between No. 5 seed Alexander Zverev and No. 32 Adrian Mannarino has started in Louis Armstrong Stadium after a delay of nearly three hours. The top-seeded Djokovic will bring a 28-match winning streak, including 25-0 this season, into his night match against Jan-Lennard Struff. After rain Thursday night suspended play on the courts without a roof, the weather is much better — sunny with the temperature around 80 degrees Fahrenheit (a little above 25 Celsius).___More AP tennis: https://apnews.com/apf-Tennis and https://twitter.com/AP_Sports Gracheva simply made too many mistakes, with 33 unforced errors — three times as many as Martic.As Gracheva’s deficit grew larger and larger, she knew more than anyone that it’s never over until it’s over: In the previous round, she trailed No. 30 Kristina Mladenovic 6-1, 5-1 and faced four match points before coming all the way back to win.There was no such turnaround this time.Martic now will try to get to the second Grand Slam quarterfinal of her career after reaching that stage at last year’s French Open. She has lost her other six fourth-round matches at major tournaments, including against Serena Williams at the U.S. Open in 2019. Also moving into the fourth round: 2016 U.S. Open champion Angelique Kerber, who beat 20-year-old American Ann Li 6-3, 6-4.Kerber’s next opponent is another American, 28th-seeded Jennifer Brady, a 6-3, 6-3 winner against Caroline Garcia.In the previous round, Garcia upset top-seeded Karolina Pliskova.___2:20 p.m. The U.S. Tennis Association described the holdup in vague terms, saying only there was “a collaborative dialogue with health officials” and that the players were “updated at all times.”The USTA said in a statement it would not provide any details because of what it called “the sensitivity of the medical issues involved.”Mannarino is part of a group of seven players under extra restrictions during the tournament because contact tracing determined they potentially could have been exposed to COVID-19 by Benoit Paire, the only entrant to test positive.___2:55 p.m.