No. 4 Philipp Kohlschreiber and No. 5 Nicolas Almagro also reached the last eight.

The 14th-ranked Stepanek was in control throughout and faced no break points. In the quarterfinals, the Czech will play either Jurgen Melzer or Dominik Hrbaty, who beat Ruben Ramirez Hidalgo of Spain 6-3, 6-4 in a first-round match.

Kohlschreiber reached his fifth ATP quarterfinal of the season when Victor Crivoi of Romania quit their match with a shoulder injury while trailing 6-2, 3-0. Kohlschreiber conceded only five points on serve and broke Crivoi four times.

The German next plays Almagro, who defeated Wayne Odesnik of the United States 6-4, 6-4. Almagro faced no break points and broke Odesnik once in each set.

In first-round play, 2008 finalist Gael Monfils beat Guillermo Garcia-Lopez of Spain 7-5, 6-4. The third-seeded Frenchman, who won his second career title in Metz last month, held serve throughout. Garcia-Lopez double-faulted on Monfils' third match point.

"I haven't much practice behind me ... physically I have to improve," said Monfils, who retained his slim chance of qualifying for the ATP World Tour Finals.

"I am not even thinking about that," Monfils said. "I am just excited to maybe win another title here and to play well."

Janko Tipsarevic defeated eighth-seeded John Inser of the United States 7-6 (4), 6-4. The Serb, who reached his first career final in Moscow last week, managed only four points on Isner's serve in the opening set before winning the tiebreaker.

"I never ever saw Isner hit one ball before the match ... had no idea how he was playing," Tipsarevic said. "He has a good forehand from the spot. I didn't play well in the first set as I didn't make him move enough."

Tipsarevic used his fifth break point in the second to close out the match with a backhand winner.

Daniel Koellerer of Austria eased past Jarkko Nieminen of Finland 6-1, 6-2 and plays 2004 champion Feliciano Lopez, who is seeded sixth, in the second round.