Halle - Roger Federer warmed up for Wimbledon by easing to victory in the second round on the Halle grass on Thursday, as he returns from a back injury that has disrupted his season.
The world number three, who dropped out of last month's French Open, had little trouble swatting aside Tunisia's Malek Jaziri, 6-3, 7-5, and next faces Belgium's David Goffin.
Federer, who is in the twilight of a sparkling career and turns 35 in August, is chasing a ninth title in Halle, Germany.
He has yet to win a title in 2016, his longest drought to start a year since he went title-less in 2000.
"I thought he was reading my serve throughout the first set. So, I started to serve a little bit different in the second set. I was having more success that way," said Federer who will be playing in a 14th Halle quarter-final.
"I was happy to come through a tough match because I thought he's tough to play against. I struggled to read his technique, the way he gets into the ball I can't really tell where he goes and I remember that from the last time I played him in Dubai, I remembered there was something but not until I got on the court. So, it was tough. I think he's a good player.
"I wish I could have played maybe a bit better at times but I must put it down to my opponent keeping me off balance as well. He was doing a really nice job of making me feel uncomfortable for a while."
Goffin set up the meeting with Federer after Ukraine's Sergiy Stakhovsky retired from their clash when trailing 4-6, 7-5, 2-0.
Federer leads Goffin 4-0 in their career head-to-heads, including a 6-2, 6-1, 6-4 win in this year's Australian Open fourth round.
Also into the next round is home hope Philipp Kohlschreiber, the eighth seed, who beat Ivo Karlovic of Croatia 6-7 (7/9), 6-4, 7-5.
The indefatigable Kohlschreiber was playing for a 10th straight day.
He won the Halle title in 2011 and next faces Austrian third seed Dominic Thiem who defeated Russia's Teymuraz Gabashvili 6-4, 6-1 for his 46th win of 2016.
Thiem beat Kohlschreiber in the Stuttgart final on Monday.
Results on Thursday at the ATP Halle grasscourt tournament (x denotes seeding):
Roger Federer (SUI x1) bt Malek Jaziri (TUN) 6-3, 7-5
David Goffin (BEL x5) bt Sergiy Stakhovsky (UKR) 4-6, 7-5, 2-0 retired
Philipp Kohlschreiber (GER x8) bt Ivo Karlovic (CRO) 6-7 (7/9), 6-4, 7-5
Dominic Thiem (AUT x3) bt Teimuraz Gabashvili (RUS) 6-4, 6-1