Defending champion Maria Sharapova and third-seeded Victoria Azarenka reached the last 16 at Roland Garros on Saturday, but piled up a combined 18 double faults and 65 unforced errors between them.

World No.2 Sharapova clinched a 6-1, 7-5 win over China’s Zheng Jie, the world number 43, in a third round clash which witnessed 11 breaks of serve.

The second seeded Russian will take on America’s Sloane Stephens for a place in the quarterfinals.

But the 26-year-old has work to do after firing down 34 unforced errors, an ugly tally which was at least partially soothed by her 25 winners.

Routine win again

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 on Saturday.

Four breaks of serve helped her to the first set.

However, two breaks took the 29-year-old from Chengdu out to a 4-1 lead in the second before the champion pulled level at 4-4, pumping up the volume at the same time.

Zheng broke back for 5-4, but she was unable to serve out the set as Sharapova levelled again at 5-5. The world number two held for 6-5 and took the tie when Zheng netted a return.

Azarenka overcame 10 double faults and 31 errors on her way to defeating France’s Alize Cornet, 4-6, 6-3, 6-1.

Nadal advances

Rafael Nadal endured another slow start on Saturday before finding his form to defeat Italy's Fabio Fognini 7-6(5), 6-4, 6-4 and qualify for the last 16.

In the end it was a comfortable enough win for the seven-time defending champion, but he was made to look sluggish on occasions. “I think he (Fognini) is a fabulous player. He attacked very well, he is very quick and when he is aggressive it is very difficult to stop him,” Nadal said.

Next up, on his 27th birthday on Monday, will be Japan's Kei Nishikori as the Spaniard continues his campaign to become the first man to win the same Grand Slam title eight times.

Nishikori defeated Benoit Paire of France 6-3, 6-7(3), 6-4, 6-1 to become the first Japanase man to reach the last 16 at Roland Garros in 75 years.

His four-set victory over Benoit Paire, saw his opponent given a penalty point for receiving coaching, prompting loud boos and jeers from the crowd packed on to court.

Foul-mouthed tirade

If it was all straightforward enough on the Philippe Chatrier centre-court, things gut unruly out on Court 7 where Serbian Janko Tipsarevic unleashed a foul-mouthed tirade at two noisy fans who kept up a running commentary during his match with Russian Youzhny.

The offending spectators were eventually sent packing, but Tipsarevic still lost 6-4, 6-4, 6-3. “There were two guys in the corner constantly taunting and laughing, and you could really see they didn't come to watch any tennis but just to pose,” said Tipsarevic.

“I just snapped, because you could really see they didn't really care, what the score was or even who was playing. They just wanted to look nice and be at the French Open. They had no respect to the players in terms of being quiet or what.”

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