DOHA, Qatar - Petra Kvitova was forced to dig deep to extend her winning streak to nine matches in Doha on Wednesday, coming from a set down to defeat Agnieszka Radwanska and reach the third round at the Qatar Total Open, 6-7(3), 6-3, 6-4.

Radwanska and Kvitova were meeting for the 12th time in their careers, and outside of four round robin matches at the WTA Finals, the match was the first thw two have played prior to the quarterfinals at any tournament.

"It was just the second round of a huge tournament, which is a bit weird for sure," Kvitova said on-court after the match. 

"It was really up and down. With Aga it's always tricky - you can serve good and still lose the game...she's just getting everything back and it's very difficult for us."

After the match, Kvitova added:  "I have no idea, first of all, how I turned it around, but I felt pretty exhausted. Not like physically but most like mentally. It's pretty tiring all these matches, but you know, on the other hand I'm very proud of myself that I won it because I don't know how, but even the first set took like hour and something...I had my chances and everything, and then I won in the third, so that was pretty good for me."

The No.16 seed ground her way to a third-round spot the hard way, needing to come from a set down after serving for the opener.

Nonetheless, it was the Czech's big serve and aggressive groundstrokes which allowed her to score her a three-set comeback victory over Radwanska for the first time since Eastbourne in 2011, as she won the last five points of the match to serve it out.

Kvitova crushed a staggering 63 winners over the course of the match and served at nearly 70% in the victory, balancing out 54 unforced errors off the ground and eight double faults.

Radwanska forced Kvitova to come up with stunning tennis more often than not, as she totaled just 12 winners and 13 unforced errors in two hours, 35 minutes.

"I tried to be more relaxed, not really think about each point. Even though I lost the first game of my serve I think the second set, then I was leading 2-1 and I felt a little bit better." Kvitova said of her comeback.

"Then the coach came, and was just a little bit easier -- my mind was a little bit off, so probably I need my mind more often off and then will be better. It can't really be like that every time, but it helped today."

For a spot in the last eight, Kvitova will face Elina Svitolina, who defeated Czech teenager Marketa Vondrousova in the first match of the day.

The pair have played seven times, and Kvitova is on a six-match winning streak in those matches, dating back to their first meeting won by the Ukrainian in Cincinnati back in 2014.

Kvitova has lost just one set in the six matches since then, but the pair have not played since Svitolina entered the Top 10 - with their last match coming at the WTA Elite Trophy in Zhuhai in 2016.

"It will be very difficult for sure. We play many times already, but it was like before. I think both of us we are in different time of our lives and career, so it will be very interesting," the Czech assessed. "I'm looking forward for the matches. It's probably why I came back to compete with those players, like Aga and Elina, so it will be a great match for me and we will see.

"I'm not a favorite of the match, so I can like just go there and play and whatever happens. I know that she's playing very well."