Top seed Serena Williams crashed out of Wimbledon at the hands of Frenchwoman Alize Cornet in a tense three-set battle.

The five-time champion lost to the French 25th seed for the second time in 2014, slipping out in the third-round clash 1-6 6-3 6-4.

For the first time since 2006, neither Serena nor Venus Williams will appear in the second week of the Wimbledon ladies' singles competition.

Williams has once again lost the chance to vie for an 18th grand slam title, the 32-year-old's last major victory remaining the 2013 US Open.

After Venus Williams bombed out to Petra Kvitova, now her sister has fallen by the wayside in the third round to boot.

Cornet reached Wimbledon's fourth round for the first time, scalping Williams again after beating the world number one in Dubai in February.

"I just cannot believe it," said a stunned Cornet.

"A few years ago I couldn't even play on grass, and now I have beaten Serena, the world number one, for the second time in a row.

"I tried to fight on every point, and follow the tactic I had in Dubai.

"I don't know how I did it, just with heart.

"She played very well, but I tried to focus and make sure I had nothing to regret.

"She helped me a bit because she made two big mistakes, she is human like everyone else and that's what I was thinking about.

"The biggest upset of the tournament because she is number one and has won so many titles at Wimbledon.

"I cannot believe that it was me that did it, I'm going to have to celebrate with my team."

Williams zipped through a rain-affected first set 6-1 on Saturday, only to watch the tide turn before her eyes as Cornet stormed home.

Nice native Cornet will now have the chance to reach uncharted grand slam territory, having never progressed beyond the fourth round of tennis' big four tournaments.

Once the 24-year-old Frenchwoman wrestled the third-round momentum, Williams' approach frayed steadily.

The match's vital moment came when Cornet converted her fourth break point in the fifth game of the final set.

No amount of fist pumping or court stalking could save Williams once Cornet imposed her superior all-round craft.

With the pivotal break secure, Cornet somehow summoned the nerve to serve out the set - and the match.

Maria Sharapova completed a clinical march through Wimbledon's first week with a straight-sets 6-3 6-0 victory over American Alison Riske.

The 2004 champion is yet to drop a set in the tournament, booking her slot in the last 16 with a routine 6-3 6-0 victory over the world number 44.

Sharapova unpicked 23-year-old Riske's game plan, overturning a break deficit in the first set and then striding to her triumph with ease.

Sharapova's sluggish start was underlined by a double fault that gifted Riske an immediate break-point chance that she did not waste.

The American's pinpoint service style right into the corner of the box then had Sharapova clambering to adjust.

Riske maintained her advantage, upholding the pressure on her Russian opponent - that was until the five-time grand slam winner rediscovered her poise to chilling effect.

The fifth seed clawed a deuce from 40-15 down on Riske's serve, then forcing a double-fault as the pressure got to the Pittsburgh native.

Acutely aware the early advantage was slipping, Riske then allowed Sharapova to break again and take control at 5-3.

The reigning French Open queen then clinched the set without issue, comfortably back in the groove.

Sharapova's ruthlessness shone through from then on in, the 27-year-old refusing to relinquish her stranglehold.

Dismissing Riske with peremptory ease, Sharapova blitzed through the second set without dropping a game.

Romanian Simona Halep, who has won seven tournaments in 13 months to charge up the rankings and earn third-seeded status at Wimbledon, might also increasingly fancy her chances of a maiden grand slam title.

She breezed to a 6-4 6-1 victory over Swiss player Belinda Bencic and will face Kazakhstan's Zarina Diyas in the fourth round.

Germany's Angelique Kerber, a Wimbledon semi-finalist in 2012, scored a fine 3-6 6-3 6-2 win over Belgian Kirsten Flipkens, who reached the last four 12 months ago.

And Eugenie Bouchard remains on course for another run deep into a grand slam, with the Canadian having already reached semi-finals in Australia and France this year.

She was too strong for German Andrea Petkovic, earning a 6-3 6-4 victory that earns her a shot at Cornet.

"I think Alize Cornet is playing good tennis," Bouchard said. "I know she beat Serena twice already this year.

"To beat the number one player in the world is no easy feat. I'm looking forward to a battle on Monday."