STUTTGART, Germany, April 17 (Reuters) - French Open champion Coco Gauff's claycourt season got off to a shaky start as she lost 6-3 5-7 6-3 to Karolina Muchova on Friday as Mirra Andreeva overpowered four-times Roland Garros winner Iga Swiatek 3-6 6-4 6-3 in the Stuttgart Open quarter-finals.
World number three Gauff, who had beaten Muchova in all six previous meetings on hard courts, committed 13 unforced errors on her forehand as she dropped a set to her Czech opponent for the first time.
The American twice Grand Slam winner bounced back to win the second set but Muchova was clinical in the third, fending off five break points as she clinched the only break in the set to take a decisive 4-2 lead.
"It's always very tough against her. She's a tough player... I think the third set was a battle. It was very physical, as well, and I'm glad I managed the first break and then I was able to keep it going," world number 12 Muchova told reporters.
Former French Open finalist Muchova will face Elina Svitolina in the semi-finals, after the fourth seed beat Linda Noskova 7-6(2) 7-5.
ANDREEVA KNOCKS OUT SWIATEK
It was the first meeting on clay between Andreeva and Swiatek, and the Russian 18-year-old broke serve in the first game before world number four Swiatek fought back with two breaks to clinch the first set.
Swiatek fought back from 2-0 down to make it 4-4 in the second set, but Andreeva held her nerve to force a decider.
Swiatek was a point away from going 3-0 up in the third set when Andreeva fought back, getting two breaks in a row to secure her third straight win over the six-times Grand Slam winner.
"I think my baseline game was fine, and I see a progress there comparing to the last tournaments. But for sure, overall, it wasn't enough," Poland's Swiatek said.
World number nine Andreeva will next face top seed Elena Rybakina or Leylah Fernandez.
(Reporting by Chiranjit Ojha in Bengaluru, editing by Ed Osmond)
