Venus Williams moved into the third round of the US Open by overcoming France's Oceane Dodin 7-5 6-4.
The 37-year-old hit 33 winners in the first match of day's three night session at Flushing Meadows.
Fourth seed Elina Svitolina saw off Katerina Siniakova 6-0 6-7 (5-7) 6-3 and next plays Evgeniya Rodina who beat Eugenie Bouchard 7-6 (7-2) 6-1.
Sloane Stephens, a semi-finalist in Toronto and Cincinnati, defeated 11th seed Dominika Cibulkova 6-2 5-7 6-3.
Eighth seed Svetlana Kuznetsova, who won at Flushing Meadows in 2004, saved three match points to prevail against Marketa Vondrousova in an entertaining encounter on Grandstand Court.
The 18-year-old Vondrousova was left in tears as she lost the final-set tie-break after struggling with cramp.
Two-time Wimbledon champion Petra Kvitova, seeded 13th, saw off Alize Cornet, who beat Heather Watson in round one, 6-1 6-2.
Fourteenth seed Kristina Mladenovic, who has gone out in the first round in her past three tournaments, continued the pattern as she lost in straight sets to Romania's Monica Niculescu.
American 20th seed Coco Vandeweghe beat compatriot Alison Riske 2-6 6-3 6-4, despite a mixed performance that saw her make 45 unforced errors, while Agnieszka Radwanska registered a 6-4 7-6 (7-3) win over Petra Martic.
Elsewhere, 25th seed Daria Gavrilova, who won her first WTA title at the Connecticut Open earlier this month, beat America's Allie Kiick in straight sets to set up a meeting with Shelby Rogers.
However, 26th seed Anett Kontaveit was beaten 6-7 (5-7) 6-1 6-4 by Czech world number 37 Lucie Safarova.