|Nadal has yet to drop a set in this year's tournament [AFP]
For anybody who still doubted it, Rafael Nadal proved he was in rude health as he bulldozed into the second week of the French Open but a dizzy Serena Williams needed the doctor to keep her challenge alive.
On a grey and cheerless day at Roland Garros, four-times champion Nadal subdued a typically belligerent Lleyton Hewitt to reach the last 16 although a comfortable looking 6-3 6-4 6-3 scoreline disguised a ferocious war of wills.
For the fourth time in five years here Hewitt, one of six Grand Slam champions illuminating Day Seven on Court Phillipe Chatrier, could punch no holes in the Nadal defences and once again there was plenty of firepower heading his way.
The fifth game of a 57-minute third set on Saturday, which spanned seven deuces and included countless intense baseline exchanges, encapsulated a two hour 28 minute contest that, if anything, proved Nadal is firing on all cylinders again after last year's early exit and subsequent knee problems.
"I played the whole match really well," Nadal, one of an unusually low group of three Spaniards to reach the fourth round, told reporters.
"Physically I'm fine. I don't have any problems so I'm happy for that."
Nadal, yet to drop a set here this year, will play Thomaz Bellucci next after the Brazilian beat Croatia's Ivan Ljubicic.
Third Novak Djokovic, continued his stealthy progress through the draw with an impressive display against Romania's Victor Hanescu, winning 6-3 3-6 6-3 6-2 on Chatrier.
Williams opened proceedings on centre court against Russian teenager Anastasia Pavlyuchenkova where the few ticket holders to arrive on time sat hunched up in jackets and hats with umbrellas at the ready as low clouds scuttled overhead.
The American, too, seemed to be affected by the chill midway through a topsy-turvy 6-1 1-6 6-2 victory that assured her of the world number one ranking at least until next month's Wimbledon.
After surrendering serve she rattled off six games to win the first set but then fell 5-0 behind in the second at which point the visibly wobbly 28-year-old called for the doctor.
"I just got a little dizzy. I don't know. I got really fatigued. I felt really dizzy out there. I was just trying just to stay in it," she told reporters.
"I've been loading up on vitamins. I should be okay, I hope."
After some early alarms in the decider when she needed an ace to stave off a break point she regained control to wrap up victory before heading home to bed.
There was no reviving sixth seed Andy Roddick, however, as the grumbling American packed up his kit bag and headed off to find some grasscourts after a third-round trouncing by Russian qualifier Teimuraz Gabashvili.
Roddick, never past the fourth round here, struggled in the cool conditions and vented his frustration at his entourage after losing his serve in the seventh game, tossing them his spare rackets with barked orders about stringing tensions.
"I fought through a couple of matches that were a little dicey but today I got outplayed from the first ball," was his brutally honest assessment after his 6-4 6-4 6-2 defeat on Court Suzanne Lenglen.
His defeat means Robby Ginepri was left flying the Stars and Stripes in the men's draw after a five-set win over former champion Juan Carlos Ferrero, one of two of the so-called Spanish armada blown off course on Saturday.
Ferrero was joined in defeat by ninth seed David Ferrer who was surprisingly beaten by Austrian Jurgen Melzer but seventh seed Fernando Verdasco did survive by beating Germany's Philipp Kohlschreiber in five sets despite breaking a toenail.
After Friday's sunshine tennis when organisers crammed the schedule with top seeds, the middle weekend began with a hangover which was not helped by the sudden-death defeat of home favourite Aravane Rezai.
Starting at 7-7 in the decider against Russian former runner-up Nadia Petrova after darkness interrupted a thrilling match the previous evening, 15th seed Rezai was back off court in 15 minutes after Petrova held her nerve to prevail 10-8.
Marion Bartoli also lost her third-round match against Israel's Shahar Peer to leave Jo-Wilfried Tsonga as the only home player left in the singles draw.
Justine Henin's hopes of winning a fifth title here, just six months after coming out of retirement, were left hanging in the balance as rain and bad light descended.
The Belgian was in a hurry to finish off fellow former world number one Maria Sharapova but after winning the opening set 6-2 she lost the second 6-3 and faces a tense Sunday.
Fourth seed Jelena Jankovic squeezed through in the nick of time, beating Ukraine's Alona Bondarenko 6-4 7-6.