Edina Gallovits-Hall surprised Erakovic 6-4, 6-4 and Alexandra Panova defeated Dulko 7-5, 6-2 in the clay-court event. Dulko was the runner-up in this tournament three years ago.
In the day's other matches, Karin Knapp survived against Catalina Castano 6-3, 2-6, 6-2 and qualifier Paula Ormaechea won over Petra Rampre 6-4, 3-6, 7-6 (7-4).
Gallovits-Hall will take on Mariana Duque-Marino in Friday's quarterfinals. The other quarterfinal matches will send Knapp against Panova, Ormaechea against Lara Arruabarrena-Vecino and Yaroslava Shvedova against Timea Babos.