War of attrition for Sharapova
Maria Sharapova survived an attritional battle against Romania's Alexandra Dulgheru to reach the third round of the US Open.
Sharapova paid the price for an erratic display in the first set and needed two hours and 38 minutes to grind out a 4-6 6-3 6-2 win over world number 95 Dulgheru.
The fifth seed will hope it is a good omen after she recovered from a set down in a succession of matches at the French Open before going on to take the title.
"We started under the sun and finished under the lights," said Sharapova. "It was tricky conditions, a tough opponent so I'm very happy I was able to come back and come through and win this match."
Second seed Simona Halep avoided the struggles of round one, when she was a set down to unranked Danielle Rose Collins, with a swift 6-2 6-1 victory over Jana Cepelova.
The Romanian is ranked in the top two at a slam for the first time, and she said: "The first round was tough because of the pressure but now I feel okay.
"I feel relaxed. I saw that even if I'm second seeded, it's like normal. It's like before. So I have just to enjoy the match and just be happy.
"I am here and I think I deserve to be here because I won many matches, good matches with top players."
Tenth seed Caroline Wozniacki was detained slightly longer but was nevertheless a comfortable 6-3 6-4 winner over Aliaksandra Sasnovich and next meets French Open semi-finalist Andrea Petkovic.
The 18th seed fought back from 5-3 down in the deciding tie-break to beat Monica Puig 3-6 6-3 7-6 (7-5) while there were straight-sets wins for Jelena Jankovic and Angelique Kerber.
Kerber next plays 17-year-old Belinda Bencic, who upset 31st seed Kurumi Nara 6-4 4-6 6-1.
Venus Williams continued her encouraging form with a 6-1 6-4 victory over Swiss Timea Bacsinszky.
The elder Williams sister has enjoyed her best season for some time, reaching the final in Montreal earlier this month, and next meets Sara Errani, who she has never lost to.
It is the first time Williams has made it through to the third round since 2010, when she went on to reach the semi-finals.
The 34-year-old said: "The last couple of years I fought really hard and I really played red-hot opponents. So it wasn't like I didn't try.
"Sometimes you don't win them. That's why you get up and you live to fight another day. So that's really what it's about for me.
"I'm happy I won a match again. Finally I did something I couldn't do the last couple of years. That's good stuff."