Defending champion Sloane Stephens avoided an early US Open exit, recovering from a set down to defeat Ukrainian qualifier Anhelina Kalinina 4-6 7-5 6-2.
Kalinina, 21, was the runner-up in the girls’ singles in 2014 and was playing in her first senior grand slam tournament after coming through qualifying.
She took advantage of errors from Stephens to win the first set and then fought back from 4-1 down in the second set to level at 5-5 but the American held firm to win her ninth successive match at Flushing Meadows.
Also on Wednesday, two-time champion Venus Williams beat Italy’s Camila Giorgi 6-4 7-5 in the second round to set up a possible third-round match against her younger sister Serena.
Venus, seeded 16th, powered through the first set but appeared to lose energy toward the end of the second in broiling conditions inside the newly built Louis Armstrong Stadium.
She said the crowd’s encouragement had helped her.
“I felt the energy, definitely,” Venus said. “That love-40 game at four all was not looking good and you guys really got me through that.”
Serena, at No. 17 seeded one spot below her older sister, should face cooler conditions during a night match against Carina Witthoeft.
If she wins, the showdown with Venus would be the earliest between the Williams sisters at a grand slam tournament since they played in the second round of the 1998 Australian Open in their very first meeting on tour.
Other seeded winners on the women’s side included No. 8 Elina Svitolina, No.15 Elise Mertens, No 19 Anastasija Sevastova and No.23 Barbora Strycova, all in straight sets.