Halle, Germany - Sixth-seeded Marcel Granollers of Spain defeated Mischa Zverev of Germany 6-4, 6-2 on Tuesday to reach the second round of the Gerry Weber Open.
The 26-year-old Granollers overcame spirited resistance from the Russian-born Zverev, who is ranked No 190.
Zverev held his serve and saved six break points before Granollers finally broke him in the ninth game to take a 5-4 lead to take the first set. The 22nd-ranked Spaniard broke the German twice in the second to wrap up the match.
Also, Radek Stepanek of the Czech Republic eliminated seventh-seeded Andreas Seppi after getting the better of two tie-breaks in the first round of the grass-court tournament.
It was the 25th-ranked Italian's fourth loss from four matches with Stepanek, ranked one place below him, and it took almost three hours by a score of 7-6 (8/6), 4-6, 7-6 (9/7).
Germany's Florian Mayer beat American qualifier Tim Smyczek 6-4, 6-4 to set up a second round meeting with five-time winner Roger Federer on Wednesday.
Rafael Nadal will open on the same day against Lukas Lacko of Slovakia, who rallied to beat Konstantin Kravchuk of Russia 2-6, 6-2, 6-3 in the first round.
Nadal won a record seventh French Open title on Monday after defeating top-ranked Novak Djokovic at Roland Garros.
Serbia's Viktor Troicki beat Benjamin Becker of Germany 6-2, 7-6 (8/6) to set up a second round meeting with third-seeded Czech Tomas Berdych, the 2007 winner.
The Gerry Weber Open is in its 20th year and seen as a warm-up event for Wimbledon.
Results on Tuesday from the Gerry Weber Open, an ATP Tour event on grass at Gerry Weber Stadion (seedings in parentheses):
Marcel Granollers (6), Spain, def. Mischa Zverev, Germany, 6-4, 6-2.
Radek Stepanek, Czech Republic, def. Andreas Seppi (7), Italy 7-6 (8/6), 4-6, 7-6 (9/7).
Florian Mayer, Germany, def. Tim Smyczek, United States, 6-4, 6-4.
Lukas Lacko, Slovakia, def. Konstantin Kravchuk, Russia, 2-6, 6-2, 6-3.
Viktor Troicki, Serbia, def. Benjamin Becker, Germany, 6-2, 7-6 (8/6).
Tommy Haas, Germany, def. Bernard Tomic, Australia, 5-2, retired.
Milos Raonic and Adil Shamasdin, Canada, def. Dustin Brown, Germany and Oliver Marach (3), Austria, 4-6, 6-2, 11-9.
Lukasz Kubot, Poland, and Mikhail Youzhny, Russia, def. Marco Chiudinelli, Switzerland and Mischa Zverev, Germany, 6-3, 4-6, 10-3.
Aisam-Ul-Haq Qureshi, Pakistan, and Jean-Julien Rojer (1), Netherlands def. Benjamin Becker and Philipp Petzschner, Germany, 6-4, 6-7 (2/7), 12-10.