Novak Djokovic battled through intense pressure from Dominic Thiem to reassert his dominance at the Australian Open Sunday, claiming a record eighth title and returning to world number one in the process.

The indomitable Serb stretched his unbeaten streak this season to 13 by rallying from two sets to one down and beating the courageous fifth-seeded Austrian 6-4, 4-6, 2-6, 6-3, 6-4 in a near four-hour ordeal.

It was his 17th Grand Slam title, moving him within two of Rafael Nadal and three of Roger Federer on the all-time list.

Victory put him alongside his fellow legends as only the third man in history to win eight or more titles at the same Slam after Nadal (12 at the French Open) and Federer (eight at Wimbledon).

It also ensured he will once again be world number one when the new rankings are released on Monday, usurping Nadal. Federer remains third with Thiem moving up a place to a career-high fourth.

But it wasn't easy with the Serb, 32, looking lethargic and out for the count in sets two and three before regaining his mojo after a medical timeout to grind down the talented, 26-year-old Thiem.

Djokovic had never before won a Slam final in seven previous attempts when finding himself two sets to one down.

But that changed this time around as the Serb drew on all his experience, keeping his foot on the gas to claim an eighth crown from the last 13 Australian Opens.