Former champions Petra Kvitova and Maria Sharapova collided in the semifinals of the year-end WTA Finals in Singapore, and it was the lefty coming out ahead 6-3, 7-6(3).

“I didn’t expect this, for sure,” Kvitova said. “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 – she played so well in the round robin group, so I expected a really tough match.

“But I knew I had the game to beat her, and that I really had to keep trying today.”

Kvitova was down 5-1 in the second set before roaring to force the tiebreaker.

“She came back in the second set and played really strong, everything well placed and strong shots,” Kvitova added. “But I was just trying to continue in the plan that I had, trying to stay aggressive and everything.

“I just took my chances and I’m really happy with the way I finished the match today.”

Sharapova will meet Kvitova later next month in the Fed Cup final.

Kvitova won the title in 2011 in her debut, and she’ll seek a second against Agnieszka Radwanska. The Pole who went 1-2 in the round robin took out WTA Finals debutant Garbine Muguruza 6-7(5), 6-3, 7-5.

“I have no words to say really,” Radwanska said.

“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.

“After two losses in the beginning I thought it was kind of over for me here. Then I was just cheering for Maria, and she did a good job helping me get to the semifinal. I hope I can keep going now.”

Radwanska had lost all four times this year to the Spaniard.

Kvitova has won six of eight against Radwanska. This will be their fifth meeting at the WTA Finals with both of Radwanska’s two wins coming at this year-end event including a year ago.

This is Radwanska’s first appearance in the WTA Finals title match, and it would be the biggest tournament victory of her career.

Unusually, both players have two losses in the event entering the final.

Muguruza went on the win her doubles semifinals with Carla Suarez Navarro. The Spaniards will meet Martina Hingis and Sania Mirza in the Sunday final.