Highly rated American youngster Taylor Fritz will face the fit-again Roger Federer in round two of the Stuttgart Open after coming from behind to win his opening match on Tuesday.

Eighteen-year-old Fritz, who had not been born when Federer first appeared in the ATP rankings in September 1997, saved a match point in the second set against Fabrice Martin before finishing strongly to triumph 3-6 7-6 (8-6) 6-1.

Fritz will now provide the first opposition for 17-time grand slam champion Federer, who is back in action this week after being forced to withdraw from the French Open due to a back problem.

Juan Martin del Potro, who has been plagued by injury troubles of his own in recent years, recorded an encouraging 6-4 6-2 win over Grigor Dimitrov in his first appearance since May's Madrid Open.

Awaiting Del Potro in round two is Australia's John Millman, who beat Lucas Pouille 6-7 (3-7) 6-3 6-4.

Pouille was one of three seeds to exit the grass-court tournament on Tuesday, Feliciano Lopez and Viktor Troicki suffering respective straight-sets losses to Mikhail Youzhny and Florian Mayer.

There were no such problems for Philipp Kohlschreiber as the veteran German triumphed 6-4 6-1 against Pierre-Hugues Herbert.

Second seed Marin Cilic will begin his campaign against 37-year-old Radek Stepanek, a victor in three sets against Denis Istomin, while Denis Kudla, Sergiy Stakhovsky and Jan-Lennard Struff are also through to round two, the latter beating Marcos Baghdatis to set up a meeting with Gilles Simon.