Aryna Sabalenka has fired a warning to the US Open field, blasting past Daria Kasatkina 6-1 6-3 to reach the quarter-finals for the third year in a row.
The Australian Open champion will also move to the top of the rankings when they are updated after the tournament and was playing with all the confidence of a world No.1, pounding Kasatkina with 31 winners.
She next plays China's Zheng Qinwen, who knocked out 2022 finalist Ons Jabeur in straight sets.
"I'm super-happy with the performance today," second seed Sabalenka said.
"It was a great match and I'm super-happy with the win."
The players traded breaks early in the first set before Sabalenka wrested the lead, breaking Kasatkina to love thanks to a series of aggressive forehand shots in the fourth game.
Kasatkina had struggled with double faults through the first three rounds and they were a problem again on Monday, as she handed Sabalenka a break with a double fault in the sixth game and again in the second set's opener.
Fifth seed Jabeur was beaten by Zheng 6-2 6-4.
An illness left Jabeur struggling to catch her breath at times earlier in the tournament and she ran out of puff against her Chinese opponent, who sent over 21 winners to reach her first grand slam quarter-final.
"Right now I feel just super-happy and excited to play in a big stadium and have a really good performance," Zheng said on court.
"That was really an amazing win for me."
Jabeur made Zheng work for the win, saving a match point in the ninth game and two more in the 10th before Zheng finally subdued the Tunisian with a sublime cross-court forehand.
Madison Keys stunned third seed Jessica Pegula 6-1 6-3 in an all-American clash to reach the quarter-final for the first time since 2018.
She will face Wimbledon champion Marketa Vondrousova, who overcame a rocky start to beat another American, Peyton Stearns, 6-7 (3-7) 6-3 6-2.
"I've had so many amazing moments in New York," said Keys, who is playing in her 12th US Open main draw.
Keys, who counts Pegula as a close friend, pumped her fist in a subdued celebration as the top-ranked American sent a forehand shot into the net on match point.
"It's always tough having to play a friend ... (but) when we get on the court it's all business," she said.
Ninth seed Vondrousova dropped the first set to Stearns but the American youngster went on to win just five more games.
"I actually didn't expect it after (Wimbledon), there was a lot of pressure," Vondrousova said. "Let's see what happens next."
There are few clues as to what might happen next for the 24-year-old Czech - she and Keys have never faced each other before.
The other women's quarter-finals pitch 2017's French Open champion Jelena Ostapenko against 19-year-old home favourite and sixth seed Coco Gauff, while Romania's Sorana Cirstea faces Karolina Muchova of the Czech Republic.