Fifth seed Petra Kvitova overcame a stern test from world number 90 Wang Yafan to make it into the US Open third round, 7-5, 6-3.
The Czech took an early 4-1 lead in the first set before allowing her opponent back into the match, but managed to turn it round.
"She played an incredible match today," Kvitova said afterwards. "There was a moment when I lost myself in the first set and she broke me. I was down and trying to fight back."
Petra Kvitova celebrates against Wang Yafan at the US Open
Image credit: Getty Images
Kvitova then took that momentum into the second set, which was a much easier task, and set up a third-round clash with the in-form Aryna Sabalenka, who beat former world number two Vera Zvonareva in straight sets.
Last year's runner-up Madison Keys had a cool win against compatriot Bernarda Pera, cruising through in straight sets, 6-4, 6-1, while 2017 French Open champion Jelena Ostapenko fought back from a set down to beat home favourite Taylor Townsend 4-6, 6-3, 6-4.