Top seed Marin Cilic stayed on course for a third ATP title this year with a comfortable victory over Spain's Feliciano Lopez in their Vienna Open quarter-final on Friday.
The Croat, a wild card replacement for injured U.S. Open champion Juan Martin del Potro, hit eight aces on his way to a 6-1, 6-4 win over the sixth seed and 2004 champion to set up a semi-final with Germany's Phillip Kohlschreiber.
Fourth seed Kohlschreiber beat number five seed Nicolas Almagro, another Spaniard, 7-5, 6-4.
Home favourite Juergen Melzer produced the day's first upset with a 6-2, 6-2 win over second seed Radek Stepanek of Czech Republic, the Austrian reaching the last fourth at the indoor hard court event for the first time in 10 attempts.
Serbia's Janko Tipsarevic, runner-up in Moscow last week, sprang another surprise when he beat third-seeded Frenchman Gael Monfils 6-4, 6-7, 6-3.