Iga Swiatek on course to become first woman since Serena Williams in 2012 to win Wimbledon and US Open in the same year.
Naomi Osaka produced a commanding performance to knock out third seed Coco Gauff 6-3, 6-2 in a highly anticipated fourth round showdown between two former US Open champions on Monday.
The result carried Osaka into the Flushing Meadows quarter-finals for the first time in five years and she will next play Czech 11th seed Karolina Muchova, who beat 27th seed Marta Kostyuk of Ukraine 6-3, 7-6(0), 6-3.
"It's really special. I look up to her a lot, the way she conducts herself is really special. To be such a role model at such a young age, I have respect for her," said Osaka, who triumphed in New York in 2018 and 2020.
Monday's showdown marked the first time that the two fan favourites met in New York since their memorable 2019 tussle when the then 15-year-old Gauff lost to Osaka.
The fans who had kept on chattering through the earlier match on Ashe fell silent as the two began their battle, with Osaka breaking Gauff from the baseline in the first game in a superb first set.
Gauff has spent many months trying to rebuild her serve and was let down by it yet again as she produced a double fault on set point, one of five across the match.
The mistakes began to pile up for the American, who handed Osaka another break point with an unforced error in the sixth game of the second set and turned helplessly to her box during the final game, telling her coaches: "Nothing's working."
The pair embraced briefly at the net after Gauff bowed out with a shot into the net on match point and Osaka smiled in a subdued celebration.
"I'm a little sensitive. I don't want to cry. I had so much fun out here," said Osaka, who has recaptured some of her best form this year with a run to the final in Montreal.
"A big thank you to my team. We've been through a lot, it hasn't been easy but they have been by my side. I love you."
Swiatek too good for Alexandrova
A laser-focused Iga Swiatek barely broke sweat as the former US Open champion methodically dismantled Russian 13th seed Ekaterina Alexandrova 6-3, 6-1 and booked her return to the quarter-finals of the Grand Slam.
The 24-year-old's crushing win on Louis Armstrong Stadium meant that she became the youngest woman to reach at least the quarterfinals of all four Grand Slams in a single season since 18-year-old Maria Sharapova managed the feat in 2005.
Swiatek was typing away furiously on her phone as she waited for her on-court interview afterwards and said she was sending a message to her coach Wim Fissette.
"I asked him to book a practice court for 10 minutes, if possible," the World No. 2 said, before she explained what worked well in helping her reach her 13th major quarter-final.
"I would say the intensity and focus. In the beginning I felt like she played fast and the court is different. I wanted to find my rhythm afterwards and I was in my bubble.
"I forced the ball to go in. I'm happy with the quality."
After an early exchange of breaks, Swiatek pounced again in the seventh game when Alexandrova's attempt at a cheeky shot at the net misfired and allowed the 2022 New York champion to bag the opening set shortly afterwards.
Six-times major winner Swiatek never looked back from there as she took control of the second set to see off Alexandrova and continue her bid to become the first woman since Serena Williams in 2012 to win Wimbledon and the US Open in the same year.
That double success would prove remarkable for a player long considered a claycourt specialist after four French Open wins.
"Now I like all of them," second seed Swiatek said of the different surfaces, adding it felt a bit "weird".
"The clay season has always been my favourite but people make it pretty hard for me with the pressure around. Sometimes it's just easier to enjoy the surfaces where it's harder to play but you have more freedom to make mistakes and accept them.
"Every month is different. I can play on every surface if I feel good in my game and in my head. I feel confident. I'll try to play good throughout the whole year."
Up next for the Polish player is either American eighth seed Amanda Anisimova, who she thrashed 6-0, 6-0 in this year's Wimbledon final, or Brazilian 18th seed Beatriz Haddad Maia.
Anisimova sweeps aside Haddad Maia
Amanda Anisimova found her best tennis under the lights at Arthur Ashe Stadium and cruised past Brazil's Beatriz Haddad Maia 6-0, 6-3 on Monday to set up a US Open quarter-final against Iga Swiatek.
The 24-year-old American said she was pleased to get the chance to earn some payback for her crushing 6-0, 6-0 loss to the world number two in the Wimbledon final in July.
"Who would've thought we'd meet again so soon?" said eighth seed Anisimova. "I'm super excited. It's going to be a great match... I hope, this time."
The American broke 18th seed Haddad Maia's serve three times to close out the opening set in under half an hour.
She took control in the second by breaking in the opening game, but the Brazilian finally got on the scoreboard by breaking back after some lapses from the American.
However, after Haddad Maia faltered on serve once more Anisimova saved two break points to hold and consolidate her lead before going on to seal victory with one final break.
"It was so great to be back to this court it's been a long time since I played here," Anisimova added. "I love playing on big stages. I'm just really enjoying it."
