Novak Djokovic beat Dominic Thiem in five sets at the Australian Open final on Sunday to win a record-extending eighth title in Melbourne and reclaim the world No 1 ranking. 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 battle. 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 No 1 when the new rankings are released on Monday, usurping Nadal. Federer remains third with Thiem moving up a place to a career-high fourth. "This is definitely my favourite court, my favourite stadium in the world and I am blessed to hold this trophy again," said Djokovic after being presented with the Norman Brookes Challenge Cup by 2005 winner Marat Safin. But it wasn't easy with the Serb looking lethargic and out for the count in sets two and three before regaining his mojo after a medical timeout. Djokovic said he felt dizzy and sapped of energy, with the trainer telling him he was dehydrated. "My energy completely collapsed. When I was tossing the ball I started to feel dizzy ... I couldn't believe what was happening," he said. Djokovic had never before won a Slam final in seven previous attempts when finding himself two sets to one down. The Serb, 32, was the overwhelming favourite, but the supremely fit and fast Thiem, 26, always had the weapons to trouble him, which he deployed successfully for much of the match, taming his serve and unleashing some explosive groundstrokes. But as he so often does, the Serb found a way. He captured the decisive break in the third game of the final set, then held firm as Thiem made desperate assaults on his serve. Going for broke in a nerve-shredding final game, the fifth seeded Austrian went for the lines but missed twice to hand Djokovic one of his most hard-earnt triumphs. "Definitely one of the toughest finals I have ever had in Australia," he said. "I was on the brink of losing the match, I didn't feel that good. Dominic was dominating from the baseline ... then I regained the strength to pull through in the fourth set, and in the fifth it was anyone's game." Four months after Nadal stopped Russian Daniil Medvedev in the US Open final, the Serb's latest title continued the 'Big Three's' reign over the majors. Djokovic, Nadal and Federer have now won 13 Grand Slam titles in succession, dating back to Federer's 2017 title at Melbourne Park. As for Thiem, the wait for a first Major goes on after losing a third Grand Slam final. He lost the last two French Open finals to Nadal. Despite this, the 26-year-old was encouraged at how close he and others, notably Medvedev and Alexander Zverev, now are to challenging for the big prizes. "I think it's only small details. In the last two finals – US Open and here – it was really close. It could have gone either way for Daniil in US Open [against Nadal] and for me here," he said, referring to Medvedev's five-setter with Nadal at Flushing Meadows. "It takes nothing more than just little bit of luck, little details here and there. "Maybe if I converted the break point in the fourth set, maybe I'm sitting here as a winner. It just takes hard work. Me and also the other young players have definitely the potential to win a Slam." While the slower clay has always been his preferred surface, beating Federer in the Indian Wells final last year was a turning point for the Austrian on hardcourts. He said he had taken a lot from the Australian Open. "I didn't have easy matches, especially from the quarters on. Beating Rafa in over four hours [in the last eight], then two days later going back out again against Sascha [Zverev]," he said. "Unbelievably intense, close match. Then two days later going out again against Novak, who won the most titles here and again played on a very high level. "I'm very aware and sure now that I can play on a very high level for a full Grand Slam ... it makes me very confident for the next big tournaments which are coming up."