Maria Sharapova advanced to the semifinals of the Porsche Grand Prix by beating Anett Kontaveit of Estonia 6-3, 6-4 Friday.
In her third match following a 15-month doping ban, Sharapova converted five of her six break points.
The Russian, who tested positive for meldonium at last year's Australian Open, will next face either Kristina Mladenovic or Carla Suarez Navarro.
Kontaveit had only five unforced errors in the first set, but Sharapova broke for a 4-3 lead and won the next two games. The Russian broke early in the second set, too, and then again for a 4-2 lead.
Sharapova finished the match with four aces to raise her total for the tournament to 24.
The five-time Grand Slam champion and former No. 1 entered the Stuttgart event on a wild card after losing her ranking because of the suspension, which had been reduced on appeal.