Maria Sharapova booked her US Open third-round berth with a gritty three-set victory over Alexandra Dulgheru.

Sharapova, who lifted her fifth grand slam title at the French Open this year, fought back from a set down to beat the Romanian world No.95 Dulgheru 4-6 6-3 6-2.

The fifth-seeded Russian was reluctant to blame the windy conditions in the cavernous Arthur Ashe Stadium court for her difficulties, which included 46 unforced errors.

And after two hours and 26 minutes on court – in a match that began in hot sunshine and ended under the floodlights – – she had her 17th three-set win of the season, the most on the WTA tour.

“It was difficult,” Sharapova said.

“Obviously the conditions were tough. You start in the sun, you finish under the lights.

“Overall I felt like in the end I was in much better shape than she was and I could have played another few sets. Mentally that helped me a lot.”

If US fans were looking for home-grown heroes to cheer among the men, they were in for a disappointment.

The first-round exits of Steve Johnson and Ryan Harrison on Wednesday meant just three American men reached the second round, the fewest in US Open history.

John Isner, the 13th-seeded US number one, Sam Querrey and wildcard Tim Smyczek all booked their second-round berths on Tuesday.

American women were keeping the flag flying, and Venus Williams did her part.

The two-time winner, who hadn’t made it past the second round in the past three years, reached the third round with a 6-1 6-4 victory over Timea Bacsinszky.

Fourth-seeded Pole Agnieszka Radwanska became the tournament’s biggest upset victim, falling 6-3 6-4 to China’s Peng Shuai.

Peng avenged a loss to Radwanska at the 2011 Australian Open where the Chinese player had held two match points.

World No.2 Simona Halep needed less than an hour to book her third-round berth, with a 6-2 6-1 victory over Slovakian Jana Cepelova.

Sixth-seeded German Angelique Kerber also advanced on cue, downing Russian Alla Kudryavtseva 6-2 6-4.