Federer will make his long-awaited return to tennis on Wednesday when he takes on either Mikhail Youzhny or Mischa Zverev in his opening match of the tournament.
The 36-year-old has not played a tennis match since March when he was surprisingly beaten in three sets by Thanasi Kokkinakis at the Miami Open.
Federer then announced he would miss the entire clay court season in a bid to stay fresh for the grass campaign.
In July, Federer will be bidding for a ninth Wimbledon title and his 21st Grand Slam victory.
But his immediate thoughts are on a successful run in Stuttgart, which is a trophy he is yet to win.
In 2016, Federer was beaten by Dominic Thiem in the semi-finals and last year he crashed out of the tournament to Tommy Haas in the first round.
However, despite being rusty, Federer is hopeful of a better performance.
“I’m back again and I’ll give my best to go deeper this year,” Federer said.
“We will see how it goes in the first match. It’ll be my first match in three months, so I’m missing some match practice.
“I think the grass is better than in the past years. Let’s hope for some better weather.”