Serena Williams became the latest victim of this year's Wimbledon giant-killings as the world number one slumped to a stunning 6-2, 1-6, 6-4 defeat against German 23rd seed Sabine Lisicki in the fourth round on Monday.

Williams followed second seed Victoria Azarenka and world number three Maria Sharapova out of the women's tournament, while defending champion Roger Federer and two-time Wimbledon winner Rafael Nadal suffered shock exits from the men's draw in the first week.

Since an embarrassing first round loss against Virginie Razzano at last year's French Open, Williams had won 77 of her 80 matches, collecting the Wimbledon, US Open, French Open and Olympic titles in the process.

The 31-year-old, a 16-time Grand Slam champion, had swept through the first week, dropping just 11 games in her opening three matches to extend her winning run to 34 matches, but she had no answer to Lisicki's big-serve and booming ground-strokes.

"I'm still shaking, I'm so happy", said Lisicki, breaking into tears.

"Serena played a fantastic match. She's such a tough opponent and it's just an amazing feeling to win."

Serena felt she let victory slip away, saying: "I definitely made too many errors, but she was playing with nothing to lose. When you play with such freedom this kind of thing can happen.

"I felt I was on the verge of winning in the third set but I was physically unable to hold serve after that."

Lisicki, a semi-finalist in 2011 who has never been past the fourth round at any other Grand Slam, will play Estonia's Kaia Kanepi for a place in the last four.

Kanepi had shattered Britain's dreams of a first woman in the Wimbledon quarter-finals for 29 years, beating unseeded Laura Robson 7-6 (8/6), 7-5.

Robson was bidding to become the first British woman to reach a Grand Slam quarter-final since Jo Durie at Wimbledon in 1984, but the Australia-born teenager left Court One crying tears of frustration.

Former champion Petra Kvitova booked her fourth consecutive Wimbledon quarter-final appearance with a 7-6 (7/5), 6-3 win over Spain's Carla Suarez Navarro.

Czech eighth seed Kvitova, who won Wimbledon in 2011, overpowered Spanish 19th seed Suarez Navarro with 23 winners and will face Belgian 20th seed Kirsten Flipkens for a place in the semi-finals.

As the highest seed remaining in the bottom half of the draw, Kvitova has a golden opportunity to reach her second Grand Slam final.

"I was pretty nervous today. There's a bit more pressure because everyone expects me to win," Kvitova said.

"I knew I had quite a good chance to beat her. I didn't play my best but it's most important to win the last point and I did."

Flipkens, the 2003 junior champion, sealed her first Grand Slam quarter-final berth with a 7-6 (7/2), 6-3 victory against Italian veteran Flavia Pennetta.

The 27-year-old, who had failed to get past the third round in five previous Wimbledon appearances, appeared overwhelmed by her success as she crouched down to kiss the grass before wiping away tears as she waved to the crowd.

Chinese sixth seed Li Na raced into the quarter-finals with a 6-2, 6-0 demolition of Italian 11th seed Roberta Vinci.

The 2011 French Open champion took just 55 minutes to win, matching her Wimbledon best, having made the quarter-finals in 2006 and 2010.

"My coach said this was a match I should win and if I can come to the quarter-final, tomorrow is a bonus. I really want to cash the bonus," Li said.

Next up for Li is Polish fourth seed Agnieszka Radwanska, last year's runner-up, who is now the highest ranked player left after a 4-6, 6-3, 6-3 win against Bulgaria's Tsvetana Pironkova.

American 17th seed Sloane Stephens reached her first quarter-final after battling back to beat Puerto Rico's Monica Puig 4-6, 7-5, 6-1

Stephens, 20, next faces French 15th seed Marion Bartoli, the runner-up in 2007, who cruised to a 6-2, 6-3 win against Karin Knapp, the Italian world number 104.