Singapore, Oct 31 (IANS): Petra Kvitova stunned Maria Sharapova to set up a championship clash against Agnieszka Radwanska at the Women's Tennis Association (WTA) Finals here on Saturday.

Kvitova came out swinging against Sharapova, 3-0, reeling off four games in a row to capture the 42-minute opening set, 6-3.

She will face Radwanska who outdid Garbine Muguruza 6-7(5), 6-3, 7-5 in a marathon semi-final earlier on Saturday.

The No.3-seeded Sharapova rebounded in a big way in the second set, storming out to a 5-1 lead, even bringing up a set point at 5-3, but the No.4-seeded Kvitova caught fire one last time, winning five of the next six games to push the set to a tie-break then taking seven of eight points from 0-2 down to close the match out in straight sets, 6-3, 7-6(3), letting out one last battle cry after match point.

"I didn't expect this, for sure," Kvitova said in her on-court interview after the match.

"I had two losses in my group, and I couldn't really believe I would play the semi-finals. 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."

The Czech looked completely down and out in the second set, but she just kept pushing.

"She came back in the second set and played really strong, everything well placed and strong shots, 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."