The world number one and top seed needed three sets to defeat American Alison Riske, but eventually won the fourth round clash 6-3, 1-6, 6-4.

Eighteenth seed Riske had won both of the previous meetings between the pair, including in the fourth round of Wimbledon last year.

But Barty overcame a slump in the middle of the match to progress and will now meet Czech player Petra Kvitová in the last eight.

The 23-year-old is seen as the best chance of becoming the first Australian singles winner in Melbourne for 42 years, with Chris O'Neil's women's victory in 1978 the last home triumph.

"It was third time a charm for me tonight," said Barty, who won her first Grand Slam at the French Open last year.

"I just had to hang in there. 

"It was very tough with both ends playing very differently. 

"I just had to give myself a chance.

"Tonight, it was important to get off to a good start. 

"I was a little bit loose, pressed too much, but I'm very proud of the way we were able to bring it back in the third, go back to the patterns I wanted to play."

Seventh seed Kvitová, the two-time Wimbledon champion, fell behind to Greece's 22nd seed Maria Sakkari before fighting back to win 6-7, 6-3, 6-2.

There was also history in the fourth round for Tunisia's Ons Jabeur, who became the first Arab woman to reach a Grand Slam quarter-final.

She knocked out China's 27th seed Wang Qiang, who had beaten American legend Serena Williams in the previous round, 7-6, 6-1.

Jabeur will play Sofia Kenin next after she ended the superb run of fellow American Coco Gauff.

Kenin, seeded 14th, had to come from behind to beat the 15-year-old, 6-7, 6-3, 6-0, and will now contest a first Grand Slam quarter-final.

Gauff's run included a shock win over Japan's defending champion Naomi Osaka in round three.

In the men's tournament, Swiss icon Roger Federer had to come from behind to reach the last eight for the 15th time.

The third seed, who was just two points from defeat in an epic five set clash with Australia's John Millman in round three, eventually beat Hungary's Márton Fucsovics 4-6, 6-1, 6-2, 6-2.

"I had to figure it out," said Federer, who is hoping to win a 21st Grand Slam title and a seventh in Australia.

"I finally found a way at the start of the second set and from there, things got a little bit easier."

Federer will play American Tennys Sandgren next, who reached a second Australian Open quarter-final by seeing off Italy's 12th seed Fabio Fognini 7-6, 7-5, 6-7, 6-4.

Serbia's defending champion Novak Djokovic enjoyed serene progression by brushing aside Argentina's 14th seed Diego Schwartzman, 6-3, 6-4, 6-4.

The second seed has 16 Grand Slam titles to his name, including a record seven at the Australian Open.

His reward is a clash with Canada's 32nd seed Milos Raonic, the former Wimbledon finalist who saw off Croatia's Marin Čilić.

Čilić, who won the US Open in 2016 and reached the Australian Open final in 2018, was brushed aside 6-4, 6-3, 7-5.

The remaining fourth round matches will take place tomorrow.