Stuttgart: Last year's runner up and home favorite, Laura Siegemund, upset second-seeded Karolina Pliskova 7-6 (3), 5-7, 6-3 at the Porsche Grand Prix in a match that lasted over three hours.
The wild card from Stuttgart next faces the fourth-seeded Simona Halep, who progressed against Anastasija Sevastova of Latvia 6-3, 6-1.
Maria Sharapova won again to move into semi-finals after beating Anett Kontaveit of Estonia 6-3, 6-4 on Friday.
In her third match following a 15-month doping ban, Sharapova converted five of her six break points.
"I'm really enjoying myself," she said.
The five-time Grand Slam champion will next face Kristina Mladenovic of France, who overcame Carla Suarez Navarro of Spain 6-3, 6-2.
Mladenovic ousted two-time defending champion Angelique Kerber on Thursday and is one of several players who has criticized Sharapova for her doping violation, but the Russian said she will not use it as added motivation in their semifinal on Saturday.
"I'm not someone that uses that as part of my comeback," Sharapova said of comments against her from her peers, adding she prefers her tennis do her talking.
"My results have spoken for everything that I should speak for. And that's all that matters. The biggest part of my comeback is what's out on the court and I will leave it at that."
Kontaveit had only five unforced errors in the first set, but Sharapova broke for 4-3 and won the next two games. The Russian broke early in the second set, too, and then again for 4-2.
Sharapova finished the match with four aces to raise her total for the tournament to 24.
"I didn't back off, I didn't back down and those are kind of the moments that I like putting myself into," said Sharapova, who won this indoor clay event three times from 2012-14.
The former No. 1 entered the Stuttgart event on a wild card after losing her ranking because of the ban.
Updated Date: Apr 29, 2017 15:35 PM