The fourth round took the court Monday, with Petra Kvitova dismissing Carla Suárez Navarro in two.
On the outside courts, Flavia Pennetta's return to the big stage was stopped by Kirsten Flipkens.
Li Na upheld her No.6 seeding with a straight set victory against the No.11 seed, Roberta Vinci.
And in an all-unseeded battle, former Top 15 player Kaia Kanepi edged Laura Robson in straight sets.
The current No.15, Marion Bartoli, beat first-time Grand Slam second weeker Karin Knapp, 62 63.
Knapp had taken down Maria Sharapova's conqueror, Michelle Larcher de Brito, in the third round.
There was one giant upset though, as Sabine Lisicki absolutely stunned Serena Williams, 62 16 64.
Williams had won 34 straight matches and was the top seed and five-time former champion at Wimbledon.
Agnieszka Radwanska dropped the first set but dodged an upset bid by Tsvetana Pironkova, 46 63 63.
The first quarterfinal on Quarterfinal Tuesday saw Lisicki dismiss Kanepi in straight sets.
Lisicki reached her second Grand Slam semifinal, having also gotten this far at Wimbledon in 2011.
Over on Centre Court, No.4 seed Radwanska and No.6 seed Li were contesting a match worthy of a final.
After over two and a half hours, Radwanska prevailed in three sets - and on her eighth match point.
Radwanska had just lost to Li in the quarterfinals of another major this year, the Aussie Open.
Back on Court 1, Bartoli was battling her hardest against the No.17 seed, Sloane Stephens.
Stephens put forth a valiant effort but ended up falling to the former World No.7 in two, 64 75.
The last quarterfinal match of the day featured No.8 seed and 2011 Wimbledon champion Kvitova.
After three grueling sets, Flipkens overcame it all, slicing and dicing her way to a 46 63 64 win.
A year ago, Flipkens couldn't even get into Wimbledon qualifying with her ranking...
And now the World No.20 will be ranked somewhere between No.16 and No.8 on next Monday's rankings.