Monica Niculescu retired from the Linz Open having suffered an injury while trailing Spain's Lara Arruabarrena 1-6, 6-1, 2-0.
The Romanian, seeded eighth, responded well after a poor opening set but was then forced to call the trainer and a medical timeout before withdrawing from the round of 32.
Arruabarrena advances to the last 16 where she will meet Belinda Bencic, who came through a gruelling match lasting two hours 21 minutes -- eventually overcoming Kirsten Flipkens 4-6, 6-2, 7-6.
Natalia Vikhlyantseva enjoyed serene progress as she swept aside Cepede Royg 6-0, 6-2 while Johanna Larsson ousted Jana Cepelova 7-6, 6-4.