Federer won the Halle title from 2003 to 2006 and again in 2008
Roger Federer eased into the Gerry Weber Open second round in Germany with a 6-4 6-4 victory over Jarkko Nieminen.
The Swiss star, who lost his world number one ranking to Rafael Nadal on Monday, is a five-time winner of the Halle grass court tournament.
Federer took just over an hour to set up a second-round match against either Colombia's Alejandro Falla or Israeli qualifier Noam Okun.
He will be chasing his seventh singles crown at Wimbledon.
Knocked out in the quarter-finals of the French Open, Federer said he was enjoying the switchover from clay to grass.
"I think any surface change has something nice about it, but grass obviously is the most special one because only one month on it," he said.
"So every day you have the chance to play on this surface is a special day. I feel it is something you want to savour as long as you are on it."
Nicolas Kiefer roused the home fans with a 4-6 6-1 7-5 win over Russian third seed Mikhail Youzhny.
Kiefer, the 1999 Halle champion, said: "I didn't play in the French Open because I had a bad feeling about my movement, so I instead used the time to get into better shape, and today I felt good."
The 32-year-old former world number four, currently ranked 181, was granted a wild card for Wimbledon on Monday.
Youzhny joins seventh seed Marcos Baghdatis and fourth-ranked Juan Carlos Ferrero in making an early exit - the latter pair both lost on Monday.
Russian second seed Nikolay Davydenko defeated Simon Greul of Germany 7-6 (7-1) 6-0 in his first competitive match since breaking his left wrist in March.
"After three months out, it was hard to come back," he said. "Training is nothing like matches, and I was so tired out there - my legs were so heavy.
"But after winning the tie-break, I was less nervous and just got better and better. I am slowly getting my self-confidence back."
Davydenko admitted he had been advised not to play in Halle since his wrist was not fully healed.
"I was not ready for the French Open because I could still feel pain and it would have been hard to come back in a five-set match," he said.
"I felt my recovery was going so slow so I decided to take a risk and come to Halle. It was my decision.
"I don't feel any pain any more and, after training for four days, I feel my wrist is now holding up."