Defending champion Roger Federer extended his unbeaten run on grass to 17 matches by beating Slovenia's Aljaz Bedene in the Halle Open first round.
The 36-year-old Swiss, who reclaimed the world number one ranking by lifting the Stuttgart title last week, won 6-3 6-4.
He dropped only eight points on his serve as he triumphed in 71 minutes.
Federer, chasing a record-extending 10th title in Halle, faces Frenchman Benoit Paire in the second round.
"I played a solid first set once I figured out how to break him," said Federer. "In the second I was able to hold all of my serves.
"For a first round and without much play on this court, it was fine. I'm very happy."
Federer's most recent defeat on grass was against Tommy Haas in Stuttgart in June 2017.
Germany's second seed Alexander Zverev lost 6-1 6-4 to Croatian Borna Corica in less than 90 minutes.
Zverev had complained about being worn down at the French Open after he won three five-set matches in succession before losing to Dominic Thiem in the quarter-finals.
A week of rest and a light training schedule were apparently not enough to revitalise the world number three.