LONDON - A gaping hole appeared in the women's draw at Wimbledon after Alize Cornet toppled top seed Serena Williams on Saturday but Rafael Nadal and Roger Federer stayed on course for a semi-final showdown after convincing wins.Follow @SlamSports
On a day of dark clouds and rain delays at the All England Club, Williams's hopes of a sixth singles title fizzled out as she sank to a 1-6 6-3 6-4 defeat against the 25th seed who celebrated her shock win by kissing the Court One turf.
World number one Williams, 32, had not fallen before the fourth round at Wimbledon since 2005 and, after returning from a four-hour rain delay, she was charging towards the second week before her power game malfunctioned.
Williams appeared hesitant as Cornet battled back with some aggressive tennis and despite showing true champions spirit to claw back two games late on there was no escape for the 17-times grand slam champion.
The result ended hopes of an eagerly anticipated last 16 match-up between Williams and fast-rising Canadian Eugenie Bouchard who comfortably beat fellow French Open semi-finalist Andrea Petkovic 6-3 6-4.
It would also have been noted with more than passing interest by fifth seed Maria Sharapova who is chasing her second Wimbledon title, 10 years after her first, and who expected to face Williams in the quarter-finals.
Russian Sharapova, who has a 1-15 record against Williams since beating her in the 2004 final, took advantage of playing under the closed Centre Court roof with a 6-3 6-0 thrashing of unseeded American Alison Riske.
Williams has now lost before the quarter-finals in all three of this year's slams and time appears to be running out on her bid to reach Steffi Graf's record haul of 22 major titles.
"I think everyone in general plays the match of their lives against me," Williams told reporters.
"I'm pretty sure that the next match, it won't be the same.
"It's okay, though. Sometimes it happens. You work hard, maybe it's not for today, maybe it's for tomorrow."
Just as in his previous two matches, Nadal offered a chink of light to an opponent on his way to the last 16 before switching on after burners to race to a 6-7(4) 6-1 6-1 6-1 win against Kazakhstan's 63rd-ranked Mikhail Kukushkin.
Swiss master Federer, seeking a record eighth Wimbledon title, continued his serene progress to the fourth round when he outclassed Colombia's Santiago Giraldo 6-3 6-1 6-3.
Federer will face Tommy Robredo on Monday after his fellow 32-year-old edged out Poland's 15th seed Jerzy Janowicz 6-2 6-4 6-7(5) 4-6 6-3 in a match ending on a virtually empty Court Two and in near darkness.
While Federer has yet to drop a set, Nadal has conceded the opener in all three rounds so far, although unlike in the previous round against Lukas Rosol, whom he lost to in 2012, he never looked in danger against Kukushkin.
Watched by a host of famous sportsmen and women in the Royal Box, including David Beckham, the 14-times grand slam champion shrugged off the loss of a first-set tiebreak to rampage through the next three sets with his best tennis of the week.
"When I played the first set I said that maybe the roof here in Wimbledon is not good for me," said the sun-loving Nadal whose 64 career titles include only two indoors.
"I don't like to be in closed places only with lights but I think I played a great match."
Nadal's next assignment will be Australian wildcard Nick Kyrgios after the 19-year-old beat fellow youngster Jiri Vesely in a battle of the former world No.1 juniors.
Kyrgios, cheered on by a legion of Australian fans, won 3-6 6-3 7-5 6-2 and is the first wildcard to reach the last 16 since Juan Carlos Ferrero in 2009.
Canadian Milos Raonic dropped only nine points on his serve as he reached the last 16 for the first time by beating Lukasz Kubot. Like Federer, and defending champion Andy Murray, dark horse Raonic is yet to drop a set.
While the weather did relent late in the day, the schedule was in tatters with two men's third round matches, Stanislas Wawrinka v Denis Istomin and Feliciano Lopez v John Isner, not starting and several others failing to finish.
Last year's runner-up Sabine Lisicki was a set ahead against Serbia's former World No.1 Ana Ivanovic when play was suspended after her heated discussion about the gathering gloom.