Venue: Roland Garros, Paris Date: 23 May-6 June
Coverage: Live video streamed from 1000 BST on BBC Sport website (UK only) and BBC red button; commentary on BBC 5 live sports extra; also live on Eurosport; text commentary on BBC Sport website
Details of BBC coverage
Serena required attention as her form suddenly dipped in the second set
Top seed Serena Williams needed medical treatment before beating Anastasia Pavlyuchenkova 6-1 1-6 6-2 to reach the last 16 of the French Open in Paris.
The world number one felt unwell after slipping 5-0 down to the 18-year-old Russian in the second set.
The American continued to move gingerly but composed herself in the decider to win in one hour and 48 minutes.
Russia's Nadia Petrova upset the home crowd with a 6-7 (2-7) 6-4 10-8 victory over France's Aravane Rezai.
Fourth seed Jelena Jankovic also advanced after a 6-4 7-6 win against Ukraine's Alona Bondarenko. The Serbian next faces Slovakia's Daniela Hantuchova, the 23rd seed.
Serena dropped her serve for only the second time in the tournament in the first game but looked set for a straightforward victory after winning the next six games to secure the first set.
But she surrendered her serve twice early in the second to give Pavlyuchenkova - a three-time Grand Slam champion in juniors - a 5-0 lead.
Serena's trainer came on court as the 28-year-old had her pulse tested and temperature taken and she continued to look sluggish as Pavlyuchenkova saw out the set.
Pavlyuchenkova saved four break points in the second game of the decider before failing to convert three of her own in the third.
But as Serena rediscovered her movement and power, the match swung decisively in her favour with successive breaks booking her place in the fourth round.
"I was a little dizzy and fatigued and just tried to stay in there. I saw a doctor after the match," said Serena.
"He told me to rest. He said there's a bug going around, players are feeling tired and getting sick the next day. But I feel a lot better now."
Serena was due to play in the women's doubles alongside sister Venus later on Sunday, but will have extra time to recover ahead of her fourth-round match after opponents Daniela Hantuchova and Caroline Wozniacki withdrew from the tournament.
Petrova, seeded two places lower than Rezai at 19, won through in a total of two hours 48 minutes of tightly fought tennis.
Petrova silenced a sparse but vocal home crowd
The match resumed at 7-7 after failing light brought a halt to proceedings on Friday night.
"We both serve well but I think that match was more mental. I wanted to serve much better and she put me under pressure," said Rezai.
"It was very tough to control the emotion. I knew I could break her and I put myself under more pressure.
"The crowd helped me, of course. I think, without them, last night I would have lost earlier."
Petrova though was unhappy with the atmosphere around the court on Friday evening and admitted she had been disrupted by the delay.
"I heard some rude comments and I wasn't happy about it," said Petrova.
"I went to bed and my heart rate was like 200. I woke up, it was about 150.
"As soon as I closed my eyes, I could see the match again and all the opportunities and what I could have done differently. But today I was in control and I knew what I had to do."
Fourth seed Jelena Jankovic successfully negotiated her way past Ukraine's Alona Bondarenko with a 6-4 7-6 (7-3) win.
The Serbian will now take on Slovakia'sHantuchova who overcame 16th seed Yanina Wickmayer 7-5 6-3 while
Marion Bartoli, the only French representative left in the women's draw after Rezai's exit, also lost as Israel's Shahar Peer ended her interest with a 7-6 (9-7) 6-2 win.
Peer will play Serena in the last 16, while Petrova will take on Venus.
Australian seventh seed Samantha Stosur took just over an hour to dispense with Russia's Anastasia Pivovarova 6-3 6-2 and set up a fourth-round match against either Maria Sharapova or Justine Henin.
Russian Alisa Kleybanova was ousted 6-2 4-6 6-0 by Kazakhstan's Yaroslava Shvedova while Jarmila Groth emerged with a 6-3 5-7 6-2 win from her all-Australian clash against Anastasia Rodionova.