Spain's Arruabarrena-Veci prevailed over Alexandra Dulgheru of Romania 7-5, 4-6, 6 -3 to reach the round of eight, where she will meet Teliana Pereira of Brazil, who rallied to best Canadian Sharon Fichman 0-6, 6 3, 6-2 Wednesday.
The news wasn't as good for Romania's Cadantu, however, who fell to No. 12 seed Sesil Karatantcheva 6-4, 5-7, 6-2.
The Bulgarian now goes on to face Catalina Castano of Colombia, who dispatched seventh-seeded Nina Bratchikova of Russia 7-6 (8-6), 6-2.
First-round winners Wednesday included sixth-seeded Ukrainian Elina Svitolina and Argentine Paula Ormaechea.