Roger Federer made a winning return to tennis on Thursday after a month away with back pain as he finished off a Stuttgart ATP grass-court match 6-4, 5-7, 6-4 over teenager Taylor Fritz.
The pair were called off court in the second round on Wednesday as heavy rains raked the Weissenhof Club, with the Swiss leading 4-3.
Federer, who last played in a third-round Rome loss to Dominic Thiem, then missed the French Open, is building for another run at Wimbledon, where he is a seven-time champion.
The world number three is making his first appearance in Stuttgart since 2001, when he played the indoor Masters.
The 34-year-old reached another milestone as his defeat of the young American hopeful marked his 1,071st victory, tying him in second place with Ivan Lendl for the Open era win record.
American Jimmy Connors holds the all-time record of 1,256 victories.
Federer will next face German Florian Mayer, a qualifier.
Fritz, the 18-year-old world number 65, made a match of it as he played toe-to-toe with the 17-time Grand Slam winner, who badly needs match play before Wimbledon starts in just over a fortnight.
Federer finished off a 29-minute opening set but found himself in a battle in the second as Fritz began gaining confidence.
The youngster broke to level matters in the final game of the second set after Federer had saved three set points.
In the third, the Swiss top seed broke for 5-4 as Fritz lost a 40-15 lead with four consecutive errors.
Federer secured the victory after one hour 40 minutes on court, having saved eight of nine break points faced.
Third seed Thiem defeated Sam Groth 7-6 (7/3), 7-6 (7/2) despite the Australian sending down 21 aces.
Thiem will line up in Friday's quarter-finals against Mikhail Youzhny after the Russian beat Sergiy Stakhovsky 6-3, 7-6 (7/1).
French fourth seed Gilles Simon beat Germany's Jan-Lennard Struff 6-4, 4-6, 6-2.