Charleston - Fifth-seeded Angelique Kerber has moved into the quarter-finals of the Family Circle Cup on Thursday with a 6-3, 6-0 victory over Lara Arruabarrena.
Kerber hadn't won more than one match in any of her previous five events.
The 27-year-old German reached the final eight for the first time since advancing to the semi-finals at Sydney three months ago.
Kerber will next face No. 13 seed Irina-Camelia Begu, who advanced when second-seeded Ekaterina Makarova withdrew Wednesday because of a stomach illness.
Defending champion Andrea Petkovic, seeded third and the highest-ranked player left at the Family Circle, faces American Madison Brengle later Thursday for a trip to the quarter-finals.
Petkovic is 9-0 at the clay-court tournament the past three years.
Top-seeded Eugenie Bouchard was defeated by American Lauren Davis on Wednesday night.
Results on Thursday in the WTA claycourt tournament at Charleston (x-denotes seeding):
Angelique Kerber (GER x5) bt Lara Arruabarrena (ESP) 6-3, 6-0
Irina Begu (ROM x13) bt Ekaterina Makarova (RUS x2) walkover