HALLE, Germany (AP) Top-seeded Roger Federer began his bid for a ninth title at the Gerry Weber Open with a routine 6-4, 7-6 (3) win over wild card Jan-Lennard Struff on Wednesday.
Federer never faced a break point and fired 11 aces to reach the second round.
Second-seeded Kei Nishikori pulled out with a rib injury. Nishikori reached the second round and was due to face Florian Mayer on Wednesday but told organizers that he was unable to play. Mayer advanced to the quarterfinals with a walkover.
Third-seeded Dominic Thiem, coming off his first title on grass in Stuttgart two days ago, beat Joao Sousa 7-5, 6-4.
In other first-round matches, eighth-seeded Philipp Kohlschreiber defeated Marcel Granollers 6-2, 7-6 (4), while Teymuraz Gabashvili beat Paolo Lorenzi 6-1, 6-4.
In a second-round match, Alexander Zverev advanced to the quarterfinals when Benjamin Becker retired with a back injury with Zverev leading 7-5, 3-0. Zverev lost the first four games of the match but recovered against his German opponent.
Andreas Seppi also reached the quarterfinals by beating qualifier Yuichi Sugita 6-3, 6-0, as well as Marcos Baghdatis, who defeated wild card Dustin Brown 7-5, 7-6 (8).
This story has been corrected to fix number of aces for Federer.