Melbourne: World number two Petra Kvitova survived a second-set meltdown to overcome Spain's Carla Suarez Navarro and reach the third round of the Australian Open on Thursday.

Kvitova won the first set easily but grew visibly frustrated as she lost the second and had to come from a break down in the third to win 6-2, 2-6, 6-4. But she said the scare was just what she needed.

"It was a very important match to have... it's good that I got through and I have won," the 21-year-old Czech said.

"For me mentally it was very tough, and I had a fight today, so it was good preparation for my next match. I know that I can fight and I can win if I'm playing badly."

The reigning Wimbledon champion was in great touch in the first set, serving well and breaking the Spaniard twice in a commanding display.

But at the start of the second, Kvitova seemed to lose focus, missing easy shots and allowing Suarez Navarro to dictate the points.

The Spaniard, one of only seven players in the top 100 with a one-handed backhand, used that shot with devastating effect to move Kvitova around the court.

Kvitova became increasingly agitated and made a string of unforced errors to surrender two breaks of serve, and with them the second set.

Suarez Navarro broke to go 2-0 ahead in the decider, but Kvitova dug deep and broke straight back when a slashing forehand landed deep in the corner.

Kvitova then unleashed a barrage of powerful ground strokes to break a second time, and held to open a vital 4-2 lead. Serving for the match at 5-4, she clinched a hard-fought victory when a Suarez Navarro backhand clipped the net and fell wide.

"In the beginning I played very well and had many winners," she said. "Then I had little mistakes and it was tough to get back because she played faster."

"I didn't know what she would play - winners or some slice or she goes to the net - so I was really a little bit confused on the court."

"I tried to get back and play more rallies and get more shots in the court."

Kvitova hit 31 winners in the match but made 48 unforced errors.

"It's my game that I'm playing winners. The mistakes are my game, it's part of my game so I know that I will have some mistakes," she said. "But today was too many."