Maria Sharapova set up a third-round clash with former French Open winner Jelena Ostapenko after beating Romania's Sorana Cirstea in New York.
The 22nd seed, who won the 2006 title at Flushing Meadows, thwarted a second-set comeback to win 6-2 7-5.
The Russian, 31, has a 21-0 win record in night matches at the US Open, recovering from a break down in the second set to finish after midnight.
"You've got to be crazy to be here after midnight," she said to fans.
The five-time Grand Slam champion hit 10 double faults and could have stayed up later with world number 51 Cirstea two points from forcing a third set, but Sharapova broke her 28-year-old opponent twice to force the win.
"There's a saying we use a lot: It's not how you start, it's how you finish," she said.
Latvia's Ostapenko is seeded 10th for the tournament and the 21-year-old fought back to beat American Taylor Townsend 4-6 6-3 6-4.
"It only gets tougher from here," said Sharapova, who suffered a 15-month doping ban in 2016.
"Being seeded in the 20s, you know you're going to get tough draws. You know you're going to play Grand Slam champions.
"[Ostapenko] is a competitor, a great opponent. I look forward to it."