Garbine Muguruza recovered from a slow start to beat Nao Hibino and reach the second round of the US Open.
The two-time Grand Slam champion, who has never made it past the fourth round in New York, won 6-4 6-4.
Playing under the roof on Louis Armstrong Stadium as rain fell on the outside courts, Muguruza fell 4-1 behind in the opening set against the world No 78.
But she found her range in time to clinch the set before making it seven games in a row to move 2-0 ahead in the second set.
Hibino battled to stay in the contest, staving off breaking points and a match point, but Muguruza eventually secured victory.
No 16 seed Elise Mertens swept into the second round with a 6-2 6-2 win over Laura Siegemund while No 22 seed Amanda Anisimova won 7-5 7-5 against Viktoriya Tomova.
Australian Open champion Sofia Kenin produced a dominant display to dispatch Belgian Yanina Wickmayer 6-2 6-2.
American Kenin, who has lifted two titles in 2020 including her maiden Grand Slam triumph in Melbourne, broke her opponent in the first game to set the tone for the match before claiming the opening set in just 37 minutes.
The 21-year-old started the second set just like the first to take an early lead and went on to serve out the match in clinical fashion.
"I knew I could dominate her," Kenin said.
Today I felt like I couldn't miss a ball. I played really good tennis and I'm proud of myself.
Second seed Kenin will next face either Russian Vera Zvonareva or Canada's Leylah Fernandez.