In his first grass-court match of the year, Federer starts his bid for a tenth Halle title against John Millman, who beat him at the US Open last year.
Grass is Federer’s best surface and in Halle his record is 63-7 and the 37-year-old says the grass simply brings out the best traits in his game.
“[Grass] highlights my strength and it maybe hides my weaknesses,” said Federer.
“From that standpoint, I can play how I want, on my terms, how I would like. When you feel that way, it is maybe what Rafa feels on the clay. I have all the options and when you have options, it gives you options to win and different tactics you can use against different players.
“That gives you maybe that little bit more margin you need to stay out of trouble and win matches.”
What time will Roger Federer play John Millman at the Halle Open today?
Federer plays Millman in the fourth match of the day on Stadion Court.
The match follows the first round clash between Jo-Wilfried Tsonga and Benoit Paire.
Federer and Millman are expected on court after 16.30 (BST).
How to watch Roger Federer vs John Millman online
Coverage of the Halle Open is being broadcast on Amazon Prime Video.
This year, Prime Video will broadcast on-site, live studio coverage across tournaments, including at the BNP Paribas Open from Indian Wells, the Fever Tree Championships from The Queens Club, the US Open, and the Nitto ATP Finals from The O2.
On-site field reporters will bring customers the latest action, analysis, and commentary right from the court side at many tournaments.
In addition to 37 ATP Tour events and the US Open available exclusively on Prime Video with a Prime membership, Prime members in the UK who subscribe to Eurosport Player through Prime Video Channels for an additional £6.99 per month (following a 7-day free trial) will also benefit from full coverage of the French Open, and daily highlights and live coverage from the men’s and women’s finals of Wimbledon in 2019.