Czech champion Petra Kvitova has fought back from a set down to book a possible Australian Open quarter-final date with world No.1 Ashleigh Barty.

Seventh seed Kvitova, runner-up to Naomi Osaka in last year’s final at Melbourne Park, was made to work before triumphing 6-7 (4-7) 6-3 6-2 over Greece’s Maria Sakkari on Rod Laver Arena.

The two-time Wimbledon champion was staring down the barrel early in the second, down a set and a break to the 22nd seed.

But her experience shone through from that point onwards in the fourth-round clash, winning 11 of the next 15 games to reach the last-eight at a grand slam for a 12th time.

“To be honest, I really don’t know,” Kvitova said when asked how she managed the stunning turnaround.

“I just keep playing. I was down a break in the first. I was able to make it to a tiebreak but obviously I lost it.

“So I really had to fight really hard. Suddenly, I just got to stop her game a little bit.

“I was playing more rallies. I was trying still to play my game but not as much risk and my serving really helped.”

Sakkari was riding a wave of history as the first Greek woman to make the fourth round of a major since Eleni Daniilidou at Wimbledon in 2005.

Having fallen to Sakkari in their past two meetings at Cincinnati and Rome last year, Kvitova was under no illusion that stopping the 24-year-old in her tracks would prove a hard task.

“It’s really tough to play Maria,” she said.

“Last time I lost to her, so I really knew it would be a difficult match.”

Kvitova will next play the winner of Sunday night’s match between top seed Barty and American world No.19 Alison Riske.