Fourth seed Alize Cornet crashed out of the Istanbul Cup on Thursday following a comeback victory from Kirsten Flipkens.
The 25-year-old Frenchwoman took the first set before dropping the second two to suffer a 2-6 6-1 6-2 loss to her Belgian opponent, who set up a quarter-final clash with Francesca Schiavone.
Italian Schiavone, who was last up on Garanti Koza Arena, knocked out fifth seed and compatriot Camila Giorgi with a straightforward 6-4 7-6 (8/6) win.
Earlier on, Ukrainian qualifier Kateryna Bondarenko held on following a second-set fightback to seal victory over Germany's Mona Barthel in an hour and 40 minutes.
The 28-year-old reached the quarter-finals with a 6-3 4-6 6-2 win over Barthel, who is ranked 64 places above her.
Eighth seed Tsvetana Pironkova of Bulgaria also advanced as she defeated Japan's Kurumi Nara 6-3 1-6 6-1 to set up a last-eight clash with Urszula Radwanska.
Source: PA