Top-seed Grigor Dimitrov overcame the highly-rated Czech Jiri Vesely to progress through to the Nastase Tiriac Trophy quarter-finals in Bucharest.
The Bulgarian defeated Vesely 7-6 (7/5) 6-2 to set up a clash against Sergiy Stakhovsky who came through 4-6 7-6 (7/5) 6-2 against Carlos Berlocq.
Defending champion Lukas Rosol made it through to the last eight after beating big-hitting Finnish star Jarkko Nieminen.
The Czech won through 6-2 6-4 by saving seven of the eight break points he faced to set up a clash with three-time champion Gilles Simon.
The Frenchman overcame home favourite Victor Hanescu 2-6 6-3 6-3 to set up a repeat of last year's semi-final.