Seeded players Hsieh Su-wei of Taiwan and Monica Niculescu of Romania were beaten Wednesday in the second round of the Strasbourg International.
The fourth-seeded Hsieh lost 6-4, 4-6, 7-6 (3) to Misaki Doi of Japan, and fifth-seeded Niculescu fell 4-6, 6-3, 6-2 to Anna Tatishvili of Georgia.
Seventh-seeded Chanelle Scheepers of South Africa reached the quarterfinals by beating American Shelby Rogers 2-6, 6-3, 6-4.
Flavia Pennetta, Johanna Larsson, Eugenie Bouchard and Lucie Hradecka also advanced to the last eight.
Later Wednesday, third-seeded Alize Cornet was scheduled to play Magda Linette.
Results from the third day of the WTA Strasbourg Open on Wednesday (x denotes seeding):
Second Round:
Eugenie Bouchard (CAN) bt Camila Giorgi (ITA) 6-3, 6-0
Chanelle Scheepers (RSA x7) bt Shelby Rogers (USA) 2-6, 6-3, 6-4
Anna Tatishvili (GEO) bt Monica Niculescu (ROM x5) 4-6, 6-3, 6-2
Alize Cornet (FRA x3) bt Magda Linette (POL) 6-3, 6-4
Flavia Pennetta (ITA) bt Mara Teresa Torro (ESP) 6-2, 6-3
Misaki Doi (JPN) bt Su-Wei Hsieh (TPE x4) 6-4, 4-6, 7-6 (7/3)
Lucie Hradecka (CZE) bt Lauren Davis (USA) 6-2, 6-2
Johanna Larsson (SWE) bt Virginie Razzano (FRA) 6-3, 6-3