Leaner, fast Kvitova looking good

Unlike her early defeat last year, she looked in great form on Thursday when beating Germany's Mona Barthel 6-2 6-4 to reach the third round.

Kvitova is looking fit and leaner and is moving well, which is an indication that new fitness coach Alex Stober, who used to work with 2014 Australian Open champion Li Na and Pete Sampras, is getting the best out of her physically.

"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," the fourth seed told reporters.

"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 (coach) David (Kotyza) 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," she added.

Kvitova began working with Stober in November and admits at first it was tough but the tough workouts are working well now.

"It's my first time actually to have this combo," she said. "When we started, the first three, four days was very, very tough. I felt everything. I couldn't really walk. Was funny to see me probably.

"But I think that every day when he did the treatments, I could handle it more and could do tougher workouts. That's helping me now."

Kvitova faces American Madison Keys in her next match.