Photo Credit:Getty Images.
Naomi Osaka was given a test by Marta Kostyuk before coming through in three sets to reach the US Open fourth round.
Japan's Osaka, 22, had to save five break points to avoid going 3-1 down in the decider but then managed to win the last five games at Flushing Meadows.
She will play 14th seed Anett Kontaveit next.
The world number nine is carrying a hamstring injury that forced her out of last week's Western and Southern Open final and wore heavy strapping on her left thigh.
Elsewhere in the women's draw, German 2016 champion Angelique Kerber beat Ann Li 6-3 6-4 and will now play American 28th seed Jennifer Brady, who saw off France's Caroline Garcia 6-3 6-3.
Garcia had knocked out top seed Karolina Pliskova in the previous round.
Czech sixth seed Petra Kvitova breezed past American Jessica Pegula 6-4, 6-3 to set up a last-16 encounter with Shelby Rogers, also of the United States.
Petra Martic won 6-3 6-3 against Russia's Varvara Gracheva and the Croatian eighth seed next faces Kazakh 23rd seed Yulia Putintseva.