Shahar Pe'er claimed 12 of the final 14 games to defeat Spain's Carla Suarez Navarro 3-6, 6-3, 6-1 and advance to the quarterfinals of the Luxembourg Open.
The 22-year-old Israeli, who is ranked number 38 in the world, dropped the first set and trailed 2-0 at the start of the second set before finding her form to knock out Suarez Navarro (32).
In the last eight, Pe'er will face Daniela Hantuchova (23), who defeated Lucie Hradecka 7-5, 3-6, 6-2 on Thursday to progress to the quarterfinals.
Meanwhile, qualifier Tsvetana Pironkova upset top-seeded Vera Zvonareva 6-0, 6-2 Thursday in the second round of the Kremlin Cup, sending Jelena Jankovic to the season-ending WTA Championships.
Jankovic, who is five points ahead of Zvonareva, will fill the final spot at the tournament in Doha, Qatar, regardless of how she finishes at the Kremlin Cup.
Serena and Venus Williams, Dinara Safina, Svetlana Kuznetsova, Elena Dementieva, Caroline Wozniacki and Victoria Azarenka have already qualified for the championships and skipped the event in Moscow. Zvonareva and Agnieszka Radwanska will go to Doha as alternates.
AP contributed to this report.