Marin Cilic of Croatia, last year's runner-up, advanced to the quarterfinals of the BMW Open on Thursday by beating Horacio Zeballos of Argentina 6-3, 7-6 (7).
Cilic fired eight aces and lost only seven points behind his first serve while breaking Zeballos's serve three times. The third-seeded Cilic is the highest seeded player left in the last eight. He has reached the quarterfinals in Munich for the fourth time in four tries.
Seventh-seeded Nikolay Davydenko of Russia rallied to beat German qualifier Julian Reister 3-6, 7-6 (5), 6-1. Davydenko won the tournament in 2004.
Cilic and Davydenko, a former No. 3 in the world, will play each other in the quarterfinals.
Another former Munich champion, Philipp Kohlschreiber, won an all-German match against ''lucky loser'' Denis Gremelmayr 6-3, 6-3.
The eighth-seeded Kohlschreiber saved the four break points he faced and converted three of six opportunities. He won the title in Munich in 2007.
In his second quarterfinal of the year, Kohlschreiber will face Radek Stepanek, who outlasted German wild card Dustin Brown 7-6 (6), 6-7 (5), 6-3 despite squandering a 5-2 lead in the second set.
Fifth-seeded Florian Mayer of Germany edged Teymuraz Gabashvili of Russia 6-4, 7-6 (1) to set up a quarterfinal showdown with Bulgarian teenager Grigor Dimitrov, who advanced on Wednesday.
In another quarterfinal Friday, Philipp Petzschner of Germany plays Potito Starace of Italy.
