Petra Kvitova to Face Agnieszka Radwanska for WTA Finals Title

 Petra Kvitova and Agnieszka Radwanska turned the WTA Finals on its head on Saturday as they ousted in-form Maria Sharapova and Garbine Muguruza to set up a surprise title match in Singapore.

Kvitova had scraped into the semis after winning just one match in the round-robin phase, but she stunned five-time Grand Slam champion Sharapova 6-3, 7-6 (7/3) to earn a shot at her second year-ending trophy.

Earlier Poland's Radwanska halted the sensational debut of Spanish world number three Garbine Muguruza 6-7 (5/7), 6-3, 7-5 to reach the final for the first time.

"I didn't expect this, for sure," Kvitova conceded after her shock win over Sharapova.

"I had two losses in my group, and I couldn't really believe I would play the semifinals. And I knew Maria would be strong today."

"But I knew I had the game to beat her, and that I really had to keep trying today," she added.

Kvitova broke fourth-ranked Sharapova three times in the first set and then recovered from 5-1 down in the second, winning five straight games and clinching victory in the tiebreak.

In the earlier semi-final, Radwanska drew on her defensive prowess and deep experience to oust the aggressive Muguruza, who is also in the doubles final and seemed to be feeling the pace.

"I have no words to say really," a tearful Radwanska, who has tried and failed six times to reach the final, told the cheering crowd at Singapore Indoor Stadium.

"I didn't know if I could come back after that first set, but I think it was a great match from the beginning until the end, so many rallies and a lot of running. I'm just so glad I could win this match in the end."

Victory on Sunday would be the biggest title of Radwanska's career, while two-time Wimbledon champion Kvitova won the tournament on debut in 2011.

Defeat to Radwanska was a setback to Muguruza, who had enhanced her growing reputation with three impressive group wins and was hoping to be the tournament's first Spanish winner.

But the Wimbledon runner-up and China Open champion, who won her last four of six with Radwanksa, was broken seven times in an off-key performance.

It was the second straight year that Radwanska has reached the semis despite only winning one group match -- but that victory this week was in straight sets over top seed Simona Halep.

After Muguruza edged the first set, Radwanska raced to a 4-0 lead in the second before the Spaniard managed to hold serve, and the Pole again seized control of the third by going 3-0 up as her opponent's errors piled up.

But Muguruza wasn't out of it and she clawed the score back to 5-5, before Radwanska prevailed and tearfully saluted the Singapore crowd.