A "hot-headed" Novak Djokovic sent an Australian Open warning to join Carlos Alcaraz and Alexander Zverev in the last 16 on Friday, but Naomi Osaka's bid for a third Melbourne crown is over with injury.

Also on day six, women's defending champion Aryna Sabalenka "pushed to the limit" to set up an intriguing showdown with teenage talent Mirra Andreeva.

Djokovic, who is chasing a record-extending 11th Melbourne title and historic 25th Grand Slam crown, is on a collision course with Alcaraz in the quarter-finals.

Both kept that tantalising prospect alive with ruthless victories.

Under new coach and old rival Andy Murray, the 37-year-old Djokovic needed four sets in both of his opening two matches.

But not this time, swatting aside Czech 26th seed Tomas Machac 6-1, 6-4, 6-4 and letting out a roar at the end.

Djokovic also pointed to his ear and then someone in the Rod Laver Arena crowd.

"I am very hot-headed right now," said the fiery Serb, but added: "This is........

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