The five-time major champion rallied from a set down to beat 95th-ranked Alexandra Dulgheru 4-6, 6-3, 6-2 in the second round of the U.S. Open on Wednesday. Sharapova overcame nine double-faults and 46 unforced errors to improve her record in three-set matches this year to 17-6.
Dulgheru had played just twice since mid-July, and she was dragging as the match approached two hours late in the second set.
On a hot, windy day, with the shadows shifting as late afternoon turned to evening, the fifth-seeded Sharapova avoided another upset on the women's side. Fourth-seeded Agnieszka Radwanska and 21st-seeded Sloane Stephens lost earlier.
"As tricky as it is, you have to expect not to play your best tennis and find a way to win," Sharapova said in an on-court interview.
The Russian star won her second French Open title in June but hasn't looked all that sharp since. Still, she hasn't lost in the second round at the U.S. Open since her Flushing Meadows debut in 2003.
Dulgheru has never been past the third round at a Grand Slam tournament and fell to 3-14 against top-10 opponents. The Romanian was ranked as high as 26th in 2011, but later missed a year because of right knee surgery.
Stephens, once a sure bet to stick around for a while at Grand Slam tournaments, suddenly can't even win there.
The 21-year-old American stumbled to her earliest loss at the U.S. Open, upset by 96th-ranked Johanna Larsson.
"Everyone goes through times like this," Stephens said. "I'm not the first person and won't be the last."
Down a set and a break, Larsson rallied to win 5-7, 6-4, 6-2 to match her best performance at a major tournament. The 26-year-old Swede had been 0-4 at Flushing Meadows before this year.
"I shouted 'Come on' a few times, not so much for myself but also to show her that I'm still here to win it," Larsson said. "I know, myself, that when you have an opponent who is fighting to the last point, it is very difficult."
When the match ended with her 63rd unforced error, Stephens was in such a hurry to leave Arthur Ashe Stadium that she briskly walked around the net to Larsson's side of the court for the handshake.
Larsson has now reached the third round at a major tournament twice this year after breaking through at the French Open.
As Stephens had climbed the rankings, the knock on her was that she would shine in the big-time tournaments and slump in other events: Her Grand Slam record coming into Wimbledon this year was 32-12, while she's 58-57 everywhere else.
Stephens reached at least the fourth round at six straight major tournaments starting with the 2013 Australian Open, when she stunned Serena Williams to make the semifinals. The longest active streak at the time, it ended with a first-round loss at Wimbledon this summer.
Now her stay at her home Grand Slam event is over quickly after she had advanced to at least the third round in three previous trips to the U.S. Open. On the verge of breaking into the top 10 last fall, Stephens has slid to No. 24 in the rankings.
Second-seeded Simona Halep had no such trouble, routing Jana Cepelova 6-2, 6-1.
Peng Shuai, ranked 39th, beat Radwanska 6-3, 6-4, giving China a big win in the U.S. Open with third-ranked Li Na out with a knee injury.
The U.S. Open is the only Grand Slam tournament in which Radwanska, the 2012 Wimbledon runner-up, has failed to reach the quarterfinals. In 2010, it was Peng who also knocked her out in the second round, the Chinese veteran's only win in four previous meetings.
"I really want to know the answer," Radwanska said. "Then maybe I will find a way to play better here and just try another way to be in the second week."
Peng had been 3-22 against top-five opponents, the last victory in 2011. But she was coming off a fourth-round showing at Wimbledon, matching her longest run at a major tournament.
On Wednesday, she won a 27-point rally with a sizzling backhand winner down the line to set up her third match point, then clinched victory with another backhand winner deep into the corner.
On the men's side, sixth-seeded Tomas Berdych swept 2001 U.S. Open champ Lleyton Hewitt 6-3, 6-4, 6-3. Seventh-seeded Grigor Dimitrov beat American Ryan Harrison 6-2, 7-6 (4), 6-2.