Zheng Qinwen beat Croatian Donna Vekic 7-6(2), 4-6, 6-2 in a rematch of their Paris Olympics title clash to reach the US Open quarter-finals after the pair battled back and forth in the latest finishing women's match in the tournament's history.
The late-night thriller at Arthur Ashe Stadium wrapped up at 2.15 am on Monday, beating the previous record for a women's match at the year's final Grand Slam by two minutes.
"It's always nice to play in the night session because I'm used to it ... It's the first time I've played here in New York at two in the morning. It's unbelievable," said Zheng.
"Thanks to the fans that aren't sleeping tonight, supporting me here."
China's Zheng is bidding to become the fourth woman to win Olympic gold and the US Open title in the same year after Serena Williams (2012), Venus Williams (2000) and Steffi Graf (1988). She will meet second seed Aryna Sabalenka next.
The 21-year-old, who lost to Sabalenka in the Australian Open final, wrapped up an intense opening set against 24th seed Vekic in an hour after raising her level a few notches in the tiebreak.
Vekic was undeterred and responded with the first break of the match early in the second set, but dropped serve immediately as Zheng heaped the pressure on her 28-year-old opponent with some heavy shots from both flanks.
Zheng's service game briefly deserted her as Vekic broke in the 10th game with a backhand winner to draw level in the match, but the Chinese player got her nose in front in the decider and held her nerve to close out the win.
"She's really tough to play on hard courts, she put a lot of pressure on me," added Zheng, who beat Vekic in straight sets in the Olympic final.
"At Roland Garros I was in control. But today she hit really aggressive. It was tough for me to play against her ... It was a really nice victory for me."
Navarro knocks out defending champ Gauff
Emma Navarro upset defending champion Coco Gauff 6-3, 4-6, 6-3 to move into the US Open quarter-finals on Sunday, beating her fellow American for the second time in a Grand Slam this year.
Gauff had been looking to avenge her defeat by Navarro at Wimbledon, where she lost in the fourth round, but the 13th seed was high on confidence as she stunned the Arthur Ashe Stadium crowd with a dominant all-round display.
Gauff was her own worst enemy, however, especially on serve where the 20-year-old third seed struggled and had 19 double faults and 60 unforced errors.
Navarro's victory moved her into a second Grand Slam quarter-final where she will play Spain's 26th seed Paula Badosa, while defeat for Gauff will see her drop out of the top five in the world rankings.
"I lost in the first round (in the) last two years and now to be making quarter-finals is pretty insane," Navarro said. "This is the city I was born in and it feels so special to be playing here.
"Coco's an amazing player and I have a ton of respect for her. I know she's going to come back here and win this thing again one year."
Gauff started poorly, serving three double faults in her opening service game as a hush descended in the crowd before she recovered, saving four break points to level the first set at 1-1.
From then on it was mainly the self-assured Navarro dictating rallies with poise while Gauff made errors playing on the defensive, handing her fellow American a 4-2 lead when she double-faulted yet again, this time on a break point.
Gauff let out a triumphant scream when she saved a set point on serve but Navarro was almost unstoppable on her own serve, taking it to love to seal the opening set.
The second set went with serve but while Navarro was well in control, Gauff was struggling and Navarro duly broke at 3-3 with a passing shot after a mad scramble to the net.
That was just the wake-up call Gauff needed as the holder suddenly switched gears and broke twice to win three games in a row and force a decider.
Gauff's celebratory roar whipped the crowd into a frenzy but their enthusiasm quickly faded and turned into groans of disappointment when she served two consecutive double faults to give Navarro a break.
Gauff nearly threw it away at 4-2 with four double faults in one game. Two more double faults while serving to stay in the match proved to be her undoing as Navarro sealed her progress when the champion's return on match point went long.
Sabalenka storms into quarters
Women's second seed Aryna Sabalenka, the runner-up to Gauff last year, continued her impressive form to move into the last eight with a 6-2, 6-4 victory over her former doubles partner Elise Mertens.
The twice Australian Open champion was in imperious form in the first set, rock solid on her booming first serve, coming into the net to great effect, and regularly unleashing her rocket of a forehand.
Belgian Mertens made things trickier in the second stanza and the Belarusian was forced to save four break points but another 23 winners to take her match tally to 41 saw Sabalenka safely into the quarter-finals for the fourth straight year.
"I really enjoy playing here," said Sabalenka, who will next face the winner of the last match of the day between Olympic champion Zheng Qinwen and Donna Vekic.
"The crowd are amazing. I really enjoying playing on these big stadiums, feel all the support. I just don't want to leave early here, you know. I just want to stay as long as I can and enjoy this beautiful court, beautiful atmosphere."
