Former Wimbledon runner-up Marion Bartoli beat seventh seed Caroline Wozniacki 7-6, 6-4 at the Stuttgart Grand Prix on Thursday to set up a quarter-final against world number three Elena Dementieva.
World number one Dinara Safina also moved into the last eight with a comfortable 6-4, 6-2 win over Daniela Hantuchova of Slovakia and will now meet Poland's Agnieszka Radwanska.
Sixth seed Nadia Petrova from Russia was sent packing by Italy's Flavia Pennetta, who beat the world number 10 6-2, 6-2 in just 58 minutes.
In a match that lasted just under two hours, France's Bartoli took her time against the 18-year-old Dane after struggling past Karolina Sprem in three sets in the previous round.
After some long exchanges on the indoor clay court, Bartoli broke world number 11 Wozniacki in the final game of the second set to clinch victory on her first match point.
The 24-year-old Bartoli, ranked 13th in the world, next plays Russia's Dementieva, who beat Hungarian Agnes Szavay 7-6, 6-1.
Szavay, the world number 32, who had beaten Dementieva in their only previous encounter, started well, breaking her in the fourth game and then holding serve to open up a 4-1 lead.
Mixing drop shots with fierce crosscourt backhands, Szavay moved the Russian around the court.
Dementieva quickly recovered to break back and level 4-4. The Hungarian carved out a set point at 6-5 which she wasted, whipping a backhand into the net before the Russian grabbed the set in the tie break.
Dementieva never looked back, steamrolling through the second set and dropping just one game.
World number four Jelena Jankovic from Serbia needed more than two hours and three sets to beat rapidly rising German talent Sabine Lisicki 7-5, 5-7, 6-3.
Fifth-seed Svetlana Kuznetsova from Russia came from a set down to beat China's Lina 4-6, 6-4, 7-5 with the Russian clinching a crucial break at 5-5 in the third to serve out the match.
Eighth-seed Agnieszka Radwanska from Poland had little trouble against Bulgarian qualifier Tsvetlana Pironkova easing 6-3, 6-3 into a last eight encounter with Safina.