Former champion Lukas Rosol reached his first quarterfinals of the year at the Nastase Tiriac Trophy when he beat Dusan Lajovic of Serbia 4-6. 6-4, 6-3 on Wednesday.
The Czech Republic's Rosol, seeded fourth, was broken four times but had the measure of Lajovic's serve.
Rosol captured his first ATP title in Bucharest in 2013, and was runner-up last year.
Countryman Jiri Vesely, the seventh seed, dominated in a 6-3, 6-1 victory over Malek Jaziri of Tunisia, winning 73 percent of his service points. He will meet either third-seeded Ivo Karlovic or rising star Borna Coric.