Petra Kvitova and Maria Sharapova progress at Australian Open

Wimbledon champion Petra Kvitova claims her Australian Open chances have been enhanced rather than harmed by her gruelling three-set battle against Carla Suarez Navarro.

Kvitova cruised through the first set and seemed on course for a routine win, only for the Spaniard to hit back, win the second and then claim an early break of serve in the decider.

Having spent the previous half hour spraying the ball all over Hisense Arena, the Czech showed commendable composure to relocate her game and break back twice to move through 6-2 2-6 6-4.

With the majority of her title rivals easing through their opening two matches, Kvitova could be forgiven for feeling she wasted precious energy on beating the world number 58.

But instead the Czech believed having a tough match could have benefits should she progress deep into the fortnight.

The second seed said: "It was very important to have a match like this in the tournament. And it's good that I came through and won for my mentality.

"It was very tough, and I fought today. So it was good preparation for the next match. I know that I can fight and I can win if I'm playing badly.

"She played very well in the second set and it was very tough for me to get back in the third.

"She was a very, very good opponent."

Kvitova's struggles were in stark contrast to Maria Sharapova's routine win over Jamie Hampton.

Fourth seed Sharapova beat the American 6-0 6-1, replicating her emphatic first-round victory over Gisela Dulko.

Although the Russian has dropped just two games in reaching the third round she was nevertheless irritated at the suggestion her record indicated a lack of depth in the women's game.

She said: "You never know what you're going to get. Sometimes we come out and we play three-set matches from the beginning, and then it's a question of 'you're top five in the world, why is someone challenging you to three sets from the beginning?'.

"I think it's just an excuse to make another story. That's really what it all comes down to.

"My goal is to go into a match and play my game. If I do it well enough and come out winning 6-0 6-1, then I've done a good job."

Adding to her three grand slam crowns remains a priority in 2012 but Sharapova also admitted doing well at this summer's London Olympics - the tennis event will be staged at Wimbledon - was a primary goal.

She said: "This year is a big year for me because I'll be playing in the Olympics, which has been a dream of mine since I was a young girl.

"Growing up in Russia, tennis wasn't a big sport back then. It was all about being an Olympian, especially the winter sports.

"Fortunately we've been able to change that a little bit and tennis has become extremely popular back in Russia.

"This year, to have a long grass-court season, will be fun."

Thirteen-time grand slam singles champion Serena Williams was pushed a little harder today, especially in the second set, before progressing courtesy of a 6-0 6-4 defeat of Barbora Zahlavova Strycova.

It was the 30-year-old's 500th career victory - a milestone of which she was justifiably proud.

She said: "It's great. It's like the ultimate. It's really, really cool.

"Five hundred is a lot of matches to play, let alone to win.

"The target is just to keep going. I never even thought about 500 till I got to Australia and realised after Brisbane I was at 498. I knew I was going to get to 500 sooner or later.

"Now I don't know what the next milestone is."

Williams' scheduled fourth-round opponent is Vera Zvonareva and the seventh seed moved a step closer to that clash with a 6-1 7-6 (7/3) victory over Lucie Hradecka.

Fifteenth seed Anastasia Pavlyuchenkova bowed out after a 5-7 6-3 6-4 defeat to American Vania King but former world number one Ana Ivanovic progressed thanks to a 6-2 6-3 win over Michaella Krajicek while 14th-seeded German Sabine Lisicki was a 6-1 6-2 victor over Shahar Peer.

Ninth seed Marion Bartoli knocked out Australian Jelena Dokic in the first of the evening matches on Rod Laver Arena.

The Frenchwoman required an hour and 12 minutes to go through 6-3 6-2.

PA