STUTTGART, Germany (AP) " Maria Sharapova won again to reach the Porsche Grand Prix quarterfinals while another major obstacle to a deep run departed on Thursday.
Two-time defending champion Angelique Kerber, who was against Sharapova receiving a wild-card entry, was upset by Kristina Mladenovic of France 6-2, 7-5.
Sharapova advanced earlier by beating fellow Russian Ekaterina Makarova 7-5, 6-1 in her second match after a 15-month doping ban.
Mladenovic won just one set in three previous matches against Kerber but dominated large parts of Thursday's match. It was the top-seeded German's first defeat in the event since 2014.
Sharapova hit nine aces and held serve throughout against Makarova. She converted three of her four break points.
"Being in the quarterfinals here again is quite special," said Sharapova, who won the indoor clay event three times from 2012-14.
Less than 24 hours after beating Roberta Vinci in straight sets in her highly anticipated first match, Sharapova said she "felt I settled down a little bit. I was able to focus on the game. I executed a great plan today and I thought I was solid."
The Russian, who tested positive for meldonium at last year's Australian Open, held off the only break point for Makarova at 5-5, and converted her second chance in the next game to close out the opening set.
Sharapova was in control of the second throughout and wrapped up the win with two straight aces to raise her total for the tournament to 20. She improved to 7-0 against Makarova.
The five-time Grand Slam champion and former No. 1, who lost her ranking due to the suspension and entered the event on a wild card, will play 73rd-ranked Anett Kontaveit of Estonia for a place in the semifinals.
Mladenovic next takes on Carla Suarez-Navarro, who beat another Russian, Elena Vesnina, 6-2, 6-4.
Also, the second-seeded Karolina Pliskova beat CoCo Vandeweghe 7-6 (2), 6-4 and will play Laura Siegemund in the quarterfinals. The finalist from last year defeated 2009 champion Svetlana Kuznetsova 6-4, 6-3.
Anastasija Sevastova beat sixth-seeded Johanna Konta 6-3, 7-5 to set up a quarterfinal against Simona Halep.