Roger Federer recovered from losing the first set against Mischa Zverev to enjoy a winning comeback at the Mercedes Cup in Stuttgart.
The world No 2 was making his first appearance on the ATP Tour since the Miami Open in March but started his grass-court campaign with a 3-6 6-4 6-2 victory.
Federer, who suffered a surprise defeat to Tommy Haas in his opening match at last year’s edition, will bid for a ninth Wimbledon title next month and is also scheduled to feature at next week’s Gerry Weber Open in Halle, live on Sky Sports Arena.
After squandering four break-point opportunities, Federer was broken to love by Zverev in the eighth game of the first set, before the German served out to take the early initiative.
Federer secured his first break of the contest on his seventh break point of the match to take a 4-2 second-set lead, but was immediately broken back by the world No 54.
Despite the setback, the 20-time Grand Slam champion recovered his composure to secure a decisive break to force a deciding set, which Federer dominated as he broke Zverev twice to secure victory on his first match point.
Federer will next face either Guido Pella or Prajnesh Gunneswaran, after the Indian qualifier earned a shock 7-6 (8-6) 2-6 6-3 victory against world No 23 Denis Shapovalov.
Meanwhile, Milos Raonic, who missed the French Open through injury, began his grass-court season in encouraging fashion with a 7-6 (10-8) 6-2 victory against Mirza Basic.
The 2016 Wimbledon finalist, who will now face Marton Fucsovics, hit 15 aces and only lost one point behind his first serve during the one-hour-and-23-minute encounter against the world No 78 from Bosnia.
German hope Maximilian Marterer maintained his impressive form from the French Open – where he lost to eventual champion Rafael Nadal in the fourth round – by securing a second-round meeting with Nick Kyrgios after overcoming lucky loser Viktor Galovic 3-6 6-4 6-1.
French second seed Lucas Pouille opened his campaign with a convincing 6-3 6-4 victory against German wildcard Rudolf Molleker and will next face Denis Istomin, after the world No 100 defeated Florian Mayer 6-3 6-4.
Feliciano Lopez booked a second-round meeting with Gilles Simon after the Spanish veteran raced through the first set against Viktor Troicki 6-1 before the Serbian retired, while Benoit Paire will face Tomas Berdych in his quarter-final encounter after a 6-7 (4-7) 6-3 6-2 win over Taylor Fritz.