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 centre 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 quarter-finals.
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."
Second set challenge
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 as her 43rd-ranked opponent failed to hold serve once while winning only nine points off the Russian's serve.
However, two breaks took the 29-year-old from Chengdu out to a 4-1 lead in the second before Sharapova turned up the heat again.
The champion pulled level at 4-4, pumping up the volume levels at the same time, only to hand Zheng the initiative again as the Chinese player 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 number two held for 6-5 and took the tie after 1hr 45min when Zheng netted a return.
Third-seeded Victoria Azarenka overcame 10 double faults and 31 unforced errors to defeat France's Alize Cornet 4-6, 6-3, 6-1 and book a place in the last 16.
The 23-year-old Australian Open champion reeled off the last six games of the match and goes on to face Italy's 2010 champion Francesca Schiavone for a quarter-final spot.
"Alize is a terrific girl. It was a difficult match and she played really well, but playing on the centre court really motivates me," said Azarenka.
In a match which featured 15 breaks of serve, it was the 23-year-old Frenchwoman, fresh from a third career title in Strasbourg on the eve of Roland Garros, who took the first set, courtesy of a big forehand off a second serve.
Cornet took a tumble in the opening game of the second set and grimaced in pain again, feeling her upper right thigh in the eighth game as Azarenka went on to level the tie.
By that stage, Azarenka, who has never got beyond the quarter-finals in Paris, had already sent down 23 unforced errors and eight double faults.
Cornet was ahead 1-0 with a break in the decider before Azarenka pulled away, winning six games on the bounce to take victory after 2hr 22min.