Kvitova sends Muguruza packing

Petra Kvitova had too much firepower for Garbine Muguruza in the quarter-finals of the Porsche Tennis Grand Prix in Stuttgart on Friday.

The fifth-seeded Czech defeated the third-seeded Spaniard 6-1, 3-6, 6-0 to reach her first WTA semifinal of the year.

Kvitova looked in total control as she broke early for a 3-1 lead and then broke again to race into a one-set lead.

But Muguruza shifted gears in the second set, adopting a more aggressive approach against Kvitova's powerful groundstrokes and it paid off. After saving a break point at 2-1 she broke in the next game and held onto her advantage to level the scores.

Kvitova would have the final say, however, totally dominating the third set and forcing her opponent into several errors as she booked her place in the last four.

"I think it's very tough because I wasn't playing bad, you know," Muguruza said after going down 6-0 in the third. "I was running and trying to fight for every point but she was coming with great shots.

"And then, I was like, I'm playing good and it's like 3-0, 4-0, 5-0. So, I know with this kind of players, with Petra if she's playing good, she hits everything."

Next up for Kvitova is local favourite and defending champion Angelique Kerber, who ended the challenge of Carla Suarez Navarro with a 6-2, 6-4 victory.

"I know how Carla is playing and she is one of the best players on clay," said Kerber. "I was trying to go for it, trying to play aggressive tennis. I knew this is the only way to beat her today and I think I did a great job."

The second semi-final sees another German, Laura Siegemund, take on tournament top seed Agnieszka Radwanska.

Having dispatched Simona Halep in the previous round, Siegemund continued her giant-killing form by ousting sixth seed Roberta Vinci 6-1, 6-4.

Radwanska, meanwhile, faced the dangerous Karolina Pliskova and fought off a spirited second-set comeback from the Czech player to prevail 6-2, 7-6 (10-8).