Maria Sharapova of Russia serves to Zheng Jie of China during their women's singles match at the French Open tennis tournament at the Roland Garros stadium in Paris June 1, 2013. [Photo/Agencies]

Russian forced to fight back in tough 2nd set against Chinese

Defending champion Maria Sharapova reached the French Open fourth round on Saturday with a 6-1, 7-5 win over China's Zheng Jie despite an up and down center court performance.

The second seeded Russian will take on America's Sloane Stephens, who she beat comfortably on clay in Rome two weeks ago, for a place in the quarterfinals.

But the 26-year-old Russian has work to do ahead of that encounter after dropping serve four times against Zheng and serving up eight double faults.

The pain of her 34 unforced errors was at least partially soothed by her 25 winners.

"I was lucky to get through that second set. I was a break down so I am happy to pull it through in straight sets," she said.

"It's not over until the last point is played and I felt like I was playing with a lot of energy out there."

Sharapova, playing in her 11th French Open, had reached the third round for the loss of just nine games and seemed on course for another routine win.

Four breaks of serve helped her to the first set as her 43rd-ranked opponent failed to hold serve once while winning only nine points off the Russian's serve.

Zheng Jie of China hits a return to Maria Sharapova of Russia during their women's singles match at the French Open tennis tournament at the Roland Garros stadium in Paris June 1, 2013. [Photo/Agencies]

The champion pulled level at 4-4, pumping up the volume level at the same time, only to hand Zheng the initiative again as the Chinese broke for 5-4.

Zheng, who became the first Chinese woman to make the last 16 of a major when she played in the fourth round in Paris in 2004, was unable to serve out the set as Sharapova broke for 5-5.

The world No 2 held for 6-5 and took the tie when Zheng netted a return.

Former No 1 Victoria Azarenka overcame a slow start and 10 double-faults to rally past Frenchwoman Alize Cornet 4-6, 6-3, 6-1 and reach the fourth round.

Seeded third, Azarenka advanced despite being broken six times. She managed a smile later when asked about her serve.

"I think I left it home today," she said. "If I can win serving like this, that's pretty remarkable."

Stephens of US, seeded 17, reached the fourth round for the second consecutive year, beating Marina Erakovic 6-4, 6-7 (5), 6-3.

Bethanie Mattek-Sands of the US reached the fourth round at a Grand Slam tournament for the second time in 27 appearances, coming back to beat 118th-ranked qualifier Paula Ormaechea of Argentina 4-6, 6-1, 6-3.

Mattek-Sands, who has been ranked as high as 30th and is currently 67th, matched her showing at Wimbledon in 2008.

She will play 12th-seeded Maria Kirilenko or unseeded Stefanie Voegele for a chance to get to a major quarterfinal for the first time.

The 28-year-old Mattek-Sands pulled off the biggest surprise of the Open so far in the second round, eliminating 2011 champion Li Na, who was seeded sixth.

Another French Open champion Francesca Schiavone easily beat 13th-seeded Marion Bartoli of France 6-2, 6-1 to reach the fourth round.

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