The world number one had suffered an abdominal injury during his third-round tie and faced a race against time to be ready for his match against Canada's Raonic at the Rod Laver Arena in Melbourne. 

Despite this, Djokovic, who is seeking his ninth Australian Open win, ground out a 7-6 (7-4), 4-6, 6-1, 6-4 victory. 

The Serbian is now set to face Germany's Alexander Zverev, who defeated another Serbian, Dušan Lajović, 6-4, 7-6 (7-5), 6-3. 

"I had no preparation for this match," said Djokovic. 

"I used every hour I had to recover since the Taylor [Fritz] match. 

"My physio and those of the Association of Tennis Professionals and Australian Open gave me their best support to get on the court. 

"I have definitely been fitter in the past and I will continue to take each day one at a time."

Bulgaria's Grigor Dimitrov stunned world number three Dominic Thiem, easing past the Austrian 6-4, 6-4, 6-0. 

A quarter-final awaits against Aslan Karatsev of Russia, who was the victor in a dramatic five-set encounter against Felix Auger-Aliassime of Canada. 

Auger-Aliassime had comfortably won the first two sets before letting his lead slip, allowing Karatsev to clinch a 3-6, 1-6, 6-3, 6-3, 6-4 result. 

In the women's tournament, seven-time Australian Open winner Serena Williams set up a quarter-final clash with world number two Simona Halep.

The United States' Williams got past Aryna Sabalenka of Belarus 6-4, 2-6, 6-4, while Romania's Halep came back from one set down to beat Poland's Iga Świątek 3-6, 6-1, 6-4. 

"You know, it's all-encompassing when you play somebody like her, and it's why such a great challenge, because she got a chance couple years ago to play her in a Wimbledon final," Halep's coach Darren Cahill said of the tie with Williams. 

"That was massive for Simona to get over that hurdle. 

"So she'll go into this match with belief, but the execution is something that depends on the day.

"And she will have belief that she can execute but she has to go out there and play as confidently as she did in the last two sets of this match, play aggressively, have that ability to try to push Serena off the baseline as much as she can."

Japan's Naomi Osaka also recovered from falling one set behind, defeating Spaniard Garbiñe Muguruza 4-6, 6-4, 7-5. 

The world number three is scheduled to meet Hsieh Su-wei of Chinese Taipei in the quarter-final.

Hsieh eased past Czech player Markéta Vondroušová 6-4, 6-2. 

Fourth-round matches are scheduled to continue in Melbourne tomorrow.