The Serbian defending champion secured his 17th Grand Slam crown with a battling 6-4, 4-6, 2-6, 6-3, 6-4 triumph at the Rod Laver Arena.

Thiem moved to within a set of winning his first Grand Slam when he took the third but Djokovic roared back with a resilient display to deny the Austrian his maiden title.

Defeat for Austria's Thiem marked his third straight loss in Grand Slam finals after he was beaten by Rafael Nadal at the French Open in 2018 and 2019.

Victory for Djokovic, the world number two, brings him closer to Roger Federer's record of 20 titles.

It was a hard-fought win for the Serbian, who clashed with the crowd and the umpire during the match.

Djokovic referenced the death of American basketball legend Kobe Bryant and bushfires which have ravaged Australia in his victory speech.

"There were some devastating things that started 2020, bushfires here in Australia, conflicts in parts of the world, and one person that I considered close in my life and was a mentor to me, Kobe Bryant, passed away," Djokovic said.

"I would like to say that this is a reminder to all of us we should stick together more than ever, be with our families, stay close to the people that love you, that care about you, there are more important things in life and it is important to be conscious and humble about things happening around you.

"This tournament sets a high standard for all the others - it is definitely my favourite in the world - and I am blessed to hold this trophy once again."

After dropping the opener, Thiem recovered and won the next two sets to the delight of the crowd inside the venue.

But Djokovic dug deep, levelling the contest by winning the fourth before taking full advantage of a tiring Thiem to clinch victory at the end of a gripping final.

He claimed the title on the first of two championship points after Thiem fired a forehand wide.

"I'm proud and happy I can compete in these times and period of tennis," Thiem said. 

"I fell short but I hope I can get revenge soon."