(CNN) -- Serena Williams continued her miserable run at grand slam tournaments in 2014 crashing to defeat against France's Alize Cornet in the third round at Wimbledon on Saturday.
The five-time champion, who lost in the second round at Roland Garros last month and in the fourth round at the Australian Open in January, looked to be on course for another routine win after taking the opening set 6-1 in a rain-interrupted match.
But Cornet, who beat Williams earlier this year in Dubai, came storming back into the match taking the second set 6-3.
With the initiative seized, Cornet drove home advantage opening up a 5-2 lead in the deciding set before Williams mounted a mini-revival to move within one game of her opponent at 5-4.
But Cornet held her nerve in the tenth game serving out to love to seal victory against the world No. 1 in just over two hours.
"To beat Serena at Wimbledon, wow, it is just a dream," 24-year-old Cornet said.
"It is the biggest upset in the tournament because she is the world number one and has won here so many times.
"I thought it was going to be tough when I lost the first set but finally I did it. I can't believe that I did it myself. It is a great moment. I've been working so hard and this is the reward."
The 25th seed will now meet Eugenie Bouchard in the fourth round following the Canadian's straight set 6-3 6-4 win over Germany's Andrea Petkovic.
Williams was left to ponder her earliest singles exit at Wimbledon since 2005 when compatriot Jill Craybas beat her at the same stage, but found time to praise her opponent.
"You know, she was going for her shots. She just played really well today," Williams said.
"I thought I was playing well. I worked really hard coming into this event. It's ok, though. Sometimes it happens. You work hard, but maybe it's not for today, maybe it's for tomorrow.
"But, yeah, so I've just got to keep going."
Williams quest for an 18th grand slam singles title will resume at Flushing Meadows in August.
Only an handful of matches were completed on Saturday as rain swept across the grounds at SW19.
Maria Sharapova dropped just three games against Alison Riske of the U.S. winning out 6-3 6-0 under the roof on Centre Court.
The reigning French Open champion will now face ninth seed Angelique Kerber in the fourth round following the German's 3-6 6-3 6-2 victory over Belgium's Kirsten Flipkens.
Simona Halep is also safely through to the second week after beating Switzerland's Belinda Bencic 6-4 6-1.
The Romanian third seed, who was runner-up to Sharapova at Roland Garros, will play Zarina Diyas from Kazakhstan.
Last year's beaten finalist, Sabine Lisicki was tied at one game all in the second set, after taking the opening set 6-4 against Serbia's Ana Ivanovic when play was stopped. The pair with resume their match on Monday.
In the men's draw both Roger Federer and Rafael Nadal are safely through to the second week.
Seven-time champion Federer was a straight sets (6-3 6-1 6-3) winner over Colombia's Santiago Giraldo.
Tommy Robredo awaits Federer in the next round after the Spaniard, seeded 23, beat Jerzy Janowicz in five sets 6-2 6-4 6-7 (7/5) 4-6 6-3.
Compatriot Nadal dropped the opening set for the third straight match before steamrollering Mikhail Kukushkin of Kazakhstan 6-7 (7/4) 6-1 6-1 6-1.
The world No. 1 will face Nick Kyrgios in round four after the Australian beat Jiri Vesely of the Czech Republic 3-6 6-3 7-5 6-2.