American third seed Jessica Pegula kept her bid for a first Grand Slam title alive by coming from a set down to beat Leylah Fernandez.
Pegula, who lost the final at Flushing Meadows two years ago to Sabalenka, came through 1-6 6-4 6-3 against the Canadian 31st seed.
Fernandez showed glimpses of the form that took her to the 2021 US Open final, where she lost to Emma Raducanu, as she raced through the first set in under 30 minutes.
But Pegula played with more patience to secure the decisive break at the end of the second set – albeit with some help from a net cord.
She saved two break points at the start of the deciding set, before breaking in the next game and going on to see out victory with a backhand volley.
“I wasn’t moving my feet up to the ball, and I was a little lazy to start off,” Pegula, 32, said.
“I was going to have to dig deep. I’m glad I was able to find somewhere there in the second set to turn it around.”
Pegula will play Romanian 16th seed Sorana Cirstea in the fourth round after she beat Italian 19th seed Jasmine Paolini 6-3 6-3.
Later, Czech seventh seed Muchova lost 6-3 7-5 to American 26th seed Navarro.
Muchova had been competing in her first tournament since undergoing minor surgery after reaching July’s Wimbledon final.
Navarro will play Ukrainian ninth seed Elina Svitolina or Russian 21st seed Anna Kalinskaya in the fourth round.
Ukrainian 11th seed Marta Kostyuk is also safely though to the last-16 after beating Ekaterina Alexandrova 6-3 6-2.
In the women’s doubles, Britons Harriet Dart and Maia Lumsden ousted Croatia’s Petra Marcinko and Ukraine’s Oleksandra Oliynykova 7-5 6-3 to reach the second round.