Sam Groth of Australia fired 15 aces to overcome Illya Marchenko of Ukraine 7-5, 6-4 in the opening round of the Mercedes Cup on Monday.
Marchenko beat Groth in their only previous match in February on a Memphis hard court, but with Stuttgart switching its courts from clay to grass, Groth got the upper hand.
Also, local wild card Michael Berrer came from behind to beat Malek Jaziri of Tunisia 6-7 (7), 6-2, 6-4.
Roger Federer is the top seed in the Wimbledon tuneup, and has a bye into the second round. Federer is coming back from a back injury that forced him to skip the French Open.