In his first match in a month, Roger Federer overcame a stiff challenge from American teenager Taylor Fritz to reach the Mercedes Cup quarter-finals in Stuttgart with a 6-4 5-7 6-4 win.

The match began the day before but was halted by rain with the top-seeded Federer leading 4-3 with a break of serve.

A return into the net by Fritz gave Federer the first set. Federer saved two set points before a forehand winner by Fritz and a forehand error by Federer gave the middle set to the 18-year-old American.

Federer struggled to hold serve early in the third but broke for 5-4 and clinched the match with a backhand winner.

“It was very difficult, just as I knew before the match,” Federer said. “I was more fortunate at the end.”

A back injury forced the 34-year-old Federer to skip the French Open, the first time he missed a Grand Slam after 65 straight appearances.

“After such a long injury, you need to find your rhythm,” Federer said.

It was Federer’s 1,071st career win on the tour, tying him with Ivan Lendl. Only Jimmy Connors has more, with 1,256.

Third-seeded Dominic Thiem, who beat Federer in the third round of the Italian Open before Federer took the injury break, edged out Australia’s Sam Groth 7-6 (7-3) 7-6 (7-2) and fourth-seeded Frenchman Gilles Simon beat Jan-Lennard Struff 6-4 4-6 6-2.

While Federer may have been rusty, second-seeded Marin Cilic was completely off, losing to the veteran qualifier Radek Stepanek 7-6 (4), 7-5.