Germany's Angelique Kerber booked her place in the quarter-finals of the Nurnberger Versicherungscup with a straight-sets win over Klara Koukalova.
The second seed claimed a 6-1 7-6 (7/2) win to set up a last-eight meeting with Japanese qualifier Misaki Doi, who fought back from a set down to see off China's Shuai Zhang 1-6 6-3 6-1.
There were wins too on Tuesday for fourth seed Roberta Vinci, sixth seed Karin Knapp and seventh seed Kurumi Nara.
Italian Vinci crushed Czech Tereza Smitkova 6-2 6-1, compatriot Knapp brushed aside home favourite Anna-Lena Friedsam 6-1 6-3 and Nara from Japan was a 6-3 6-4 winner over Switzerland's Stefanie Voegele.
Source: PA
