Pegula, the No. 3 seed, is still trying to advance beyond the quarterfinals of a Grand Slam tournament. First, she’ll have to get by the 2017 runner-up in Flushing Meadows who also needed three sets to move on.
Keys came back to eliminate No. 14 Liudmila Samsonova 5-7, 6-2, 6-2.
Ons Jabeur, the No. 5 seed who lost in the finals last year, also reached the fourth round by outlasting No. 31 Marie Bouzkova 5-7, 7-6 (5), 6-3 in a match that took 2 hours, 56 minutes. Jabeur will face No. 23 Zheng Qinwen of China, who edged Lucia Bronzetti 6-3, 4-6, 6-4.
Pegula and Keys could have met early in both Montreal and Cincinnati, but Keys had to withdraw with a hip injury in Canada — where Pegula won the title — and lost her opening match in Ohio. So they’ve still played only once, a victory for Pegula last year in San Diego, although the Americans sometimes hit together.
“Every time I practice with her, she just has the ability to just hit aces and rip forehands and backhands, play a really big power game,” Pegula said. “It will be interesting to see how smart I can play and what I can do to combat that.”
Other winners on the women’s side Saturday included No. 2 Aryna Sabalenka, who routed Clara Burel 6-1, 6-1, and No. 13 Daria Kasatkina, who topped Greet Minnen 6-3, 6-4 and will face the Australian Open champion Monday. Wimbledon champion Marketa Vondrousova, the No. 9 seed, routed No. 22 Ekaterina Alexandrova 6-2, 6-1 and will face unseeded American Peyton Stearns.
Pegula found herself in a tough test with Svitolina, the No. 26 seed from Ukraine who reached the U.S. Open semifinals in 2019. It was tied 2-2 in the third set before the 29-year-old from Florida broke serve to start a run of four straight games to win the match.
That put her in the fourth round of the U.S. Open for the second time. Pegula had her best result at the tournament in 2022, falling to eventual champion Iga Swiatek in the quarterfinals. She’s gone that far in each Grand Slam tournament but is still seeking to reach the final four.