WIMBLEDON, England -- On the verge of victory, Maria Sharapova briefly lost her bearings.
Sharapova's old serving problems resurfaced Thursday at Wimbledon, costing her the second set before she recovered to beat dangerous Tsvetana Pironkova, 7-6 (3), 6-7 (3), 6-0.
Azarenka converted five of her six break points and saved all four she faced to reach the third round for the sixth time in seven appearances at the All England Club.
The Belarusian reached the semifinals in 2011 and is looking for her second Gram Slam title after winning the Australian Open this year as part of a 26-match winning streak to start the season.
The two players had only met once, with Oprandi winning 6-1, 6-1 on clay in 2007.
The No. 1-ranked Sharapova saved five set points in the first set and led the second set 3-1 when play was halted Tuesday because of darkness. She lost the first two games when the match resumed\ and double-faulted on her first three service points in the tiebreaker.
"It felt like two matches in a way," Sharapova said. "Today I wanted to start off really well because I knew I was up a break. Didn't go according to plan. Really served sloppy."
Sharapova underwent shoulder surgery in 2008, and has been prone to double-faults, but in the final set she had no trouble with her serve -- or anything else. She won 21 of the last 27 points and finished with just 11 unforced errors.
Sharapova said she didn't make any major changes down the stretch.
"We were playing with the same balls; I played with the same racket," she said. "I just started doing things a little bit better."
Pironkova, ranked 38th, beat Venus Williams at Wimbledon each of the past two years.
"If she played on grass 365 days a year, she'd be top 5 probably," Sharapova said. "She has the perfect game for it."
But Sharapova's at her best in winner-take-all sets. She improved her record in three-set matches to 9-0 this year and 21-1 since the beginning of 2011.
She has won 14 consecutive matches, including the French Open this month to complete a career Grand Slam.
While Sharapova battled an erratic serve, with eight aces and 10 double-faults, four-time champion Serena Williams had no such trouble. She won 27 of 28 points on her first serve, including 10 aces, and never faced a break point. Czink twice whiffed on returns.
"I love my serve," Williams said, "and I love feeling good when I serve."
The sixth-seeded Williams could meet Sharapova in the final next week. A 17-year-old Sharapova defeated Williams for the Wimbledon title in 2004.
Kvitova breezed through the first set in just 22 minutes and broke two more times in the second against the 101st-ranked Baltacha.
Kvitova beat Sharapova in last year's final but has yet to reach a title match in 2012, although she reached the semifinals of both the Australian Open and French Open. She hit 23 winners compared to nine for Baltacha.
Others advancing included No. 28-seeded Christina McHale.
Sara Errani committed only five unforced errors and beat Anne Keothavong of Britain 6-1, 6-1. The 25-year-old Errani, an Italian who has blossomed in Grand Slam competition this year, matched her best Wimbledon showing by advancing to the third round.
She was the French Open runner-up this month to Sharapova, and she's 12-2 in major tournaments in 2012. She began this year with a career record of 15-17 at majors.
Playing the day's first match on Court 2, the 10th-seeded Errani erased all three break points she faced and won in 61 minutes. That was a grueling effort compared with Wednesday, when she played only one point to complete a victory suspended overnight because of rain.
McHale eliminated Mathilde Johansson 7-5, 7-5.
The 28th-seeded McHale, a 20-year-old from Englewood Cliffs, N.J., struggled a bit to close out her 7-5, 7-5 second-round victory over Johansson.
"It was weird: The first and second sets went exactly the same. I am still not finding my best tennis consistently over the two matches I have played," McHale said. "I was just staying in there, taking advantage when she does make some unforced errors and then just staying with it when she is playing really well. I still feel I can be a lot more offensive."
Next up for the American is a match against eighth-seeded Kerber of Germany.
"I'm going to have to return her lefty serve well, try and take advantage when I can, and not let her be dictating," McHale said.
The American got some compliments Thursday from Serena Williams, who was asked about McHale and called her "so tough; she has a great game."
Lepchenko joins Williams, McHale and unseeded Sloane Stephens to make the last 32 at the All England Club.
The 53rd-ranked Lepchenko is coming off her best career Grand Slam result by reaching the fourth round at the French Open.
She will play 24th-seeded Francesca Schiavone of Italy in the third round.
Lepchenko, who was born in Uzbekistan, has lived in the United States since 2001, and became an American citizen in September.
The fourth day of play began with sunshine and temperatures heading into the low 80s.
Information from The Associated Press contributed to this report.