Vienna - Ivo Karlovic of Croatia has reached his sixth quarter-final of the season after beating two-time former champion Jurgen Melzer 6-4, 7-6 (1) at the Erste Bank Open on Wednesday.
The sixth-seeded Karlovic, who served 21 aces, broke Melzer at 2-2 in the opening set, shortly after the Austrian was treated for dizziness.
The second set went without service breaks into a tiebreaker after Karlovic saved a set point for Melzer at 5-4.
Karlovic next plays either top-seeded David Ferrer or Tobias Kamke of Germany, who rallied to defeat Simone Bolleli of Italy 3-6, 6-3, 6-4.
The fifth-seeded Lukas Rosol of the Czech Republic beat Lukas Lacko of Slovakia 6-2, 6-4 to set up a second-round match against Viktor Troicki of Serbia.
Results on Tuesday from the ATP Austrian Open (x denotes seeding):
Robin Haase (NED) bt Dominic Thiem (AUT x8) 6-3, 3-6, 6-3
Vasek Pospisil (CAN) bt Daniel Brands (GER) 6-3, 6-7 (3/7), 7-6 (7/2)
Viktor Troicki (SRB) bt Vctor Estrella (DOM) 6-0, 6-3
Jurgen Melzer (AUT) bt Norbert Gombos (SVK) 3-6, 6-3, 6-3
Ivo Karlovic (CRO x6) bt Federico Del Bonis (ARG) 6-7 (1/7), 7-6 (11/9), 7-6 (7/2)
Benjamin Becker (GER) bt Victor Hanescu (ROM) 4-6, 6-1, 6-3
Thomaz Belluci (BRA) bt Paul-Henri Mathieu (FRA) 6-1, 6-4
Jan-Lennard Struff (GER) bt Guillermo Garca-Lopez (ESP x7) 6-3, 6-4
Tobias Kamke (GER) bt Simone Bolelli (ITA) 3-6, 6-3, 6-4