Two-time Wimbledon champion Petra Kvitova became the first player to advance to the Australian Open quarterfinals.
She rallied from a set and a break down to win 6-7 (4), 6-3, 6-2 over Maria Sakkari.
''From the beginning, it was a lot of nerves out there. I didn't feel the best. I was just, you know, too tight and everything was flying,'' Kvitova said.
Eventually, she worked out the issues, began to swing more freely and took control.
Kvitova's quarterfinal opponent will be No. 1 seed Ash Barty - trying to become the first Australian to win the nation's Grand Slam tournament since the 1970s.