Second seed Vera Zvonareva became the latest women's seed to fall after a comprehensive 6-2 6-3 third-round defeat by Tsvetana Pironkova.
Bulgarian Pironkova was the surprise package in last year's tournament, reaching the semi-finals where she was knocked out by Russian Zvonareva.
But the 32nd seed avenged that defeat as Zvonareva's game crumbled on Court Two, with 18 unforced errors.
Top seed Caroline Wozniacki and Venus Williams also progressed on Friday.
Dane Wozniacki, who has yet to win a Grand Slam, wrapped a 6-1 6-3 victory over Virginie Razzano in 66 minutes, making just one unforced error on Court Two.
She will play Australia's 27th seed Jarmila Gajdosova in the third round.
Five-time Wimbledon champion Williams was in equally impressive form, sweeping aside Spain's Maria Jose Martinez Sanchez 6-0 6-2, setting up a fourth-round tie against Pironkova.
Ninth seed Marion Bartoli survived three match points to beat Lourdes Dominguez Lino 4-6 7-5 6-2.
The unseeded Spaniard, ranked 48th in the world, served for the match at 5-4 in the second set but Bartoli, who lost to Venus Williams in the 2007 Wimbledon final, displayed impressive resilience to level the match and break her opponent's serve in the next game before levelling.
And she sealed victory with a commanding performance in the final set to set up a third-round match against Italy's 21st seed Flavia Pennetta.
Wozniacki was at her imperious best, extending her career record against Frenchwoman Razzano to 5-0.
"I served pretty well today and... dictated quite a few of the points," she said. "I was happy about the game."
Wozniacki has reached the fourth round at Wimbledon for the past two years, but has never made it to the quarter-finals.
In the third round, former French and US Open champion Svetlana Kuznetsova, the 12th seed, suffered a 4-6 6-3 6-4 defeat by Belgium's 19th seed Carolina Wickmayer.
Germany's 11th seed Andrea Petkovic will also take no further part in the women's singles after a 6-4 7-6 defeat by Russia's Ksenia Pervak, currently ranked 89th in the world.
Fourth seed Victoria Azarenka took advantage of a late-afternoon rain delay to clinch a three-set victory over Daniela Hantuchova on Centre Court.
The match was tied at one set all with Hantuchova serving at 2-1 down when the rain came, forcing the players off court while the roof was closed.
When play resumed, Azarenka was clearly fired up and pounced on Hantuchova's serve to claim what proved to be the decisive break.
The Belarusian went on to win 6-3 3-6 6-2 and will meet Nadia Petrova in the fourth round.
"[The rain break] probably was to my advantage - I stayed composed and went out there very motivated and focused," she said.
Former world number three Petrova, unseeded at SW19, also advanced into the next round following a 6-3 6-2 win over Kateryna Bondarenko.
Petrova will be joined by eighth seed Petra Kvitova, who beat Italy's Roberta Vinci 6-3 6-3.
Meanwhile, sixth seed Franscesca Schiavone was 3-2 down to Tamira Paszek in a third-set decider when rain suspended play on Court 12.