Aryna Sabalenka finally got rolling after a bad beginning to the latest-starting match in US Open history, regrouping to beat No. 29 Ekaterina Alexandrova 2-6, 6-1, 6-2 early Saturday and reach the fourth round.
The No. 2 seed didn't hit the first shot of the match until 12:07 a.m. and had dropped the first set barely a half-hour later. But she seized control early in the second set, winning 10 straight games to open a 5-0 lead in the third.
The runner-up last year in Flushing Meadows eventually finished off the victory at 1:48 a.m., tied for the second-latest ending to a women's match at the US Open, and advanced to face No. 33 seed Elise Mertens on Sunday.
"I was happy that I was able to stay focused, no matter what, and I was able to turn around this match," Sabalenka said.
The previous latest start to a match at the US Open was exactly at midnight on Sept. 2, 1987, with Gabriela Sabatini going on to beat Beverly Bowes 6-3, 6-3.
The night session at Arthur Ashe Stadium began more than an hour after its usual 7 p.m. starting time following Frances Tiafoe's victory over Ben Shelton in the afternoon that lasted 4 hours, 3 minutes.
Under a new late-night match policy the tournament debuted this year, the tournament referee can move any match that hasn't gone on by 11:15. Instead, Sabalenka and Alexandrova were kept on Ashe, finally getting on the court after defending champion Novak Djokovic was shocked by No. 28 seed Alexei Popyrin in four sets..
A U.S. Tennis Association spokesman said tournament officials kept the Grandstand available in the event they wanted to move the Sabalenka-Alexandrova match. A decision was going to be made by the end of the fourth set of the Djokovic-Popyrin match.
Sabalenka said her desire was to remain on Ashe, though she would prefer it be in the opener of the night session and put the men second.
The bigger problem was the quick start by Alexandrova, who broke Sabalenka's serve twice in the first set.
"She just crushed it. She played so well," Sabalenka said.
But once Sabalenka broke for a 3-1 lead in the second set, she got going quickly from there to wrap it up earlier than the latest end of a women's match, when Maria Sakkari finished off Bianca Andreescu at 2:13 a.m. on Sept. 6, 2021.
Sabalenka hoped to be in bed by 4 a.m. and sleep as long as she could.
"Technically, I did my practice session today, so I'm good for tomorrow, right?" she joked. "Can I just tell my team that? It's 2 a.m.; we count it like today."
In other women's matches, No. 26 seed Paula Badosa came back from a set down and staved off a match point late in the third set to reach the round of 16 at the US Open for the first time.
Badosa ultimately prevailed against Romanian qualifier Elena-Gabriela Ruse in a third-set tiebreak 4-6, 6-1, 7-6 (8).
It was the second deciding-set tiebreak played on the women's side this tournament; Ena Shibahara defeated Daria Saville in the first round.
Badosa has now reached the round of 16 at all four majors. She is the fifth Spanish woman in the Open era to reach the fourth round at all four Slams, following Garbine Muguruza, Conchita Martínez, Carla Suarez Navarro and Arantxa Sánchez-Vicario.
Badosa next faces China's Wang Yafan, who on Friday ousted No. 20 seed Victoria Azarenka 6-4, 3-6, 6-1. Azarenka, a three-time US Open finalist, committed 32 unforced errors and dropped serve six times in the 2-hour, 22-minute match.
American Emma Navarro, the No. 13 seed, needed three sets but got past No. 19 Marta Kostyuk of Ukraine 6-4, 4-6, 6-3. Up next for Navarro is a Wimbledon rematch with No. 3 Coco Gauff in the round of 16.
"I did a good job of neutralizing her serve and just playing really aggressive from the baseline and pushing back against her groundstrokes," Navarro, who is from South Carolina and won an NCAA title for Virginia, said about that matchup last month. "And then always getting one more ball back in the court."
Mertens advanced after defeating 2017 finalist Madison Keys 6-7 (5), 7-5, 6-4 in a tightly fought contest.
Keys, who reached the semifinals a year ago, started strong but could not break through Mertens' defenses in the end as she was unable to convert on five break-point chances in the final set.
No. 7 seed Zheng Qinwen, the 2024 Olympic singles gold medalist and Australian Open runner-up, shook off slow starts in her first two matches and took down unseeded German Jule Niemeier 6-2, 6-1 to reach the round of 16 for a second straight year.
"Finally, it's the first match I won in two sets. ... It's not [been] easy for me to play after the Olympic Games," said Zheng, who has noted previous struggles with focus after deep tournament runs. "I'm starting to find my tennis and to play better and better."
Zheng is the second Chinese woman in the Open era to reach the round of 16 in back-to-back US Opens, joining Li Na, who did so in 2008 and 2009.
Zheng next faces Donna Vekic, whom she defeated in the gold-medal match in Paris. Since 1988, the only other matchup to occur both at the US Open and in the Olympic singles gold medal match was Steffi Graf vs. Sabatini in 1988. The US Open final was played right before the Seoul Olympics, and Graf beat Sabatini both events. Tennis returned to the Olympic program in 1988 after a long hiatus.
Vekic, who beat American Peyton Stearns 7-5, 6-4, said she was optimistic she would do better against Zheng on New York's hard courts just a few weeks after coming off second best on clay at the Paris Games.
"She played an unbelievable match in Paris. She was too good that match. I had couple of chances but didn't manage to pull them off," the 24th seed told reporters. "But it's a new match. We're a couple of weeks later. It's a different surface, thankfully for me."
ESPN Stats & Information, The Associated Press and Reuters contributed to this report.