Roger Federer faced down local battler John Millman 4-6 7-6(2) 6-4 4-6 7-6(8) in a five-set thriller to reach the last 16 of the Australian Open and restore some normality to Melbourne Park after a day of big upsets.

The 20-times Grand Slam champion made an extraordinary 82 unforced errors to go with 62 winners as he went toe-to-toe with the world number 47 over more than four hours on Rod Laver Arena to secure his 100th Australian Open victory.

Millman, who got the better of the Swiss at the 2018 U.S. Open, had all the early momentum and won the opening set before Federer grabbed the second on a tiebreak and the third with a late break of serve.

The tireless Australian was never going to fold, however, and took the fourth set before forcing the third seed to battle back from a break down to seal the victory in the tiebreak.

Stefanos Tsitsipas will not be repeating his heroics from the Australian Open 12 months ago after losing in the third round to Milos Raonic.

The Greek captivated Melbourne last year with his run to the semi-finals, including victory over Roger Federer in the fourth round.

But big-serving Canadian Raonic, who has endured wretched luck with injuries over the last few years, was resurgent and thoroughly deserved his 7-5 6-4 7-6 (2) victory.

Raonic will next face 2018 finalist Marin Cilic, who is unseeded this year but enjoying a fine tournament, with his latest victory coming in five sets over Roberto Bautista Agut.

There were no problems, though, for defending champion Novak Djokovic, who produced a serving masterclass to defeat Yoshihito Nishioka 6-3 6-2 6-2.

The second seed hit 17 aces and lost just eight points on serve during the match, seven of them in the third set.

Djokovic, who has former Wimbledon champion Goran Ivanisevic among his team, said: "I love playing on the court. I like the conditions. I'm starting to feel very, very comfortable and compact on the court. I'm going to try to keep that going."

In the fourth round, Djokovic will face 14th seed Diego Schwartzman, who beat Dusan Lajovic 6-2 6-3 7-6 (7).

Hungary's Marton Fucsovics continued his fine tournament with a 6-1 6-1 6-4 victory over Tommy Paul while Tennys Sandgren, who reached the quarter-finals two years ago, defeated fellow American Sam Querrey 6-4 6-4 6-4.