Kvitova continues form.

Czech rising star Petra Kvitova has announced herself as a real threat to the top seeds by toppling Italian Flavia Pennetta in three sets, 3-6 6-3 6-3.

The Hisense Arena crowd were treated to a tense match today that could very well have swung in either direction. But it was Kvitova, who was building on the form that saw her take out Aussie favourite Sam Stosur two days ago that fought the hardest.

The first set was all about Pennetta, with the left-handed Kvitova struggling to match the Italian's power. 22nd seed Pennetta was attacking from the baseline early and she used her fierce backhand to produce several big winners. Kvitova's power came from her backhand too, but she couldn't match it with her accuracy.

Kvitova said she didn't dwell too much on the first set loss as she tried to concentrate on the task at hand. "Well, I was very nervous in the first set. I thought that it will be fighting, and it was, so I just wanted to try for just focus on each point. But all match was very close and very tough."

With the Italian leading the charge, it appeared early on that it would be a brief match. But Kvitova had other ideas and took the reins in the second. The tall Czech owned the net on several points with Pennetta unable to get past her. Her serve became more of a weapon too and she forced a third set.

The chase was on in the third with both women hungry for a quarterfinals berth. Kvitova ran her opponent to each corner of the court, but Pennetta maintained her form. Power and timing were her strengths but the world No.28 Czech had the answers. It may have taken her a while to find her groove, but once she did Kvitova was unbeatable. She took the third set 6-3.

The shy Czech said she focused on each point individually instead of the overall match. "When I served, each game was very close. It was deuce or something. But I made the big points also. I improve also my serve and just think about the point and I think around."

Kvitova believes that there is one very important part of her game that helps her. "The left-handed has something good for the serve or something. So, yeah, it's good for us."

At just 20-years-old, Kvitova has had an awesome start to 2011. She beat Andrea Petkovic to win the Brisbane International two weeks ago and now moves into the quarters of Australian Open 2011. She faces second seed Vera Zvonareva in what promises to be a colossal battle to move into the semifinals.