Petra Kvitova has claimed that the changes she made to her training schedule during the off-season have improved her chances of winning the Australian Open title.

The fourth seed failed to reach the third round in Melbourne in the previous two years before passing that stage with a win over Mona Barthel on Thursday, and the two-time Wimbledon champion believes that she is better prepared physically for the heat thanks to extra work with coach David Kotyza and fitness trainer Alex Stober.

"I think it was quite warm today and I think I handled it quite well. The last two or three years I'm not sure if I can handle it like that," Kvitova told reporters after beating Barthel.

"It's always tough to breathe a little bit when it's really warm. But because I had this time during the off-season I knew I could still play.

"When I knew today would be warmer than yesterday, I knew that David was little bit worried. Me, too, of course. I did not say it, but I knew that I'm prepared better than the years before, I can handle it better."

Kvitova will take on Madison Keys in the third round on Saturday.