Russia’s Ekaterina Makarova has sent former finalist Agnieszka Radwanska crashing to a surprise exit at Wimbledon, while giant-killer Barbora Zahlavova Strycova claimed another famous scalp.
Makarova, the 22nd seed, had never been past the third round in her six previous appearances at Wimbledon.
But the 26-year-old, a quarter-finalist at the Australian and French Opens last year, destroyed the world number four 6-3 6-0 and will play Czech 23rd seed Lucie Safarova for a place in the semi-finals.
Radwanska’s exit means three of the top four seeds have been eliminated from the women’s draw following the defeats of Williams and Li Na.
Earlier, Zahlavova Strycova moved into the last eight with a 6-2 7-5 victory against former world number one Caroline Wozniacki.
Zahlavova Strycova, the world number 43, had enjoyed the best win of her career in the previous round when she defeated Chinese second seed Li and she added Danish 16th seed Wozniacki to her list of upsets.
The 28-year-old, who served a six-month ban for doping last year, will play compatriot Petra Kvitova for a place in the semi-finals.
Asked about her revival after the drugs suspension, Zahlavova Strycova admitted she almost quit after testing positive for banned stimulant sibutramine at the 2012 Luxembourg Open.
“I didn’t want to play again because I felt like it’s a little bit unfair,” she said.
“In the first two months, I didn’t want to come back. It was tough, but on the other hand, it also brings me some positive things. I am seeing the sport a little bit different now. And here I am.”
Sixth seed Kvitova, who won the Wimbledon title in 2011, routed world number 61 Peng Shuai of China 6-3 6-2 in just one hour.
The 24-year-old has now reached the last eight at Wimbledon for five successive years.
Three of the four quarter-finalists in the bottom half of the draw are Czech after Safarova ended the fairytale run of world number 175 Tereza Smitkova, a 19-year-old who was the lowest ranked woman left in the tournament, with a 6-0 6-2 victory in just 47 minutes.
Safarova will face Makarova in her first Wimbledon quarter-final appearance, which will also be the 27-year-old’s first last-eight clash at a Grand Slam since 2007.
Canadian star Eugenie Bouchard also booked her first appearance in the quarter-finals as the 13th seed defeated Alize Cornet 7-6 7-5.
The 20-year-old underlined her growing reputation by seeing off French 25th seed Cornet, who had caused one of the great Wimbledon upsets in the previous round when she defeated world number one Williams.
After reaching the semi-finals at the Australian and French Opens already this year, Bouchard will faces either world number five Maria Sharapova or German ninth seed Angelique Kerber in the last eight after their match was delayed for a day by London’s inclement weather.
“It’s great to be in the quarters at Wimbledon, that’s what I work so hard for,” Bouchard said. “But I want to go one step further so I have to keep focused.”
Sabine Lisicki, last year’s beaten finalist, finally downed former world number one Ana Ivanovic on Monday to give herself a place in the last 16.
In a third round match called off for bad light on Saturday, and then interrupted by rain early on Monday, the German 19th seed eventually beat the Serbian 11th seed 6-4 3-6 6-1.
She faces Kazakhstan’s Yaroslava Shvedova on Tuesday for a place in the quarter-finals.