Novak Djokovic won a record-extending 10th Australian Open title on Sunday despite battling an injury that would have forced most players to quit, his coach Goran Ivanisevic said, adding that the world number one kept getting "crazier and crazier".

Djokovic, who defeated Stefanos Tsitsipas 6-3 7-6(4) 7-6(5) and won a 22nd Grand Slam title to match Rafa Nadal, has had to deal with suspicion about the severity of his hamstring injury, which he suffered en route to winning the warm-up title in Adelaide.

The 35-year-old Serb said this week that questions over whether he has genuinely been struggling only served to give him extra motivation.

"Let me put it like this. I don't say 100%, but 97% of the players, on Saturday when you get results of the MRI, you go straight to the referee office and pull out of the tournament. But not him," Ivanisevic told reporters.

"He gave everything... Every day was kind of better and better. I didn't expect this. Okay, first two rounds okay, but then against (Grigor) Dimitrov I was very scared. But he got through and in the end he won the tournament.

"... He's getting crazier and crazier, I can say that (laughter). It's no end of the field of craziness. In a positive way, I mean (smiling)."

Despite dominating the match, Djokovic grew frustrated with Tsitsipas's resilience at one point and began mouthing off at his coach, but Ivanisevic said the exchange of words was water under the bridge.

"I was also a tennis player. I was also little bit crazy. I understand how he feels. I understand the emotions," Ivanisevic said.

"This is the final of a Grand Slam. I don't mind. If this going to help him, we already talked about it so many times. I told him, 'you can tell me whatever you want, but you have to win, otherwise you have a problem'.

"It's the same as if you are a football coach of Real Madrid, you need to have the pressure. If you don't win one, two games, you get fired. Only Grand Slam counts. But it's a good challenge."

Ivanisevic also hailed the incredible rivalry between Djokovic and Nadal, likening their growing Grand Slam tallies to the score of a handball match.

"It's a battle of Spain against Serbia... 22-22 for the moment. Now it's going to be interesting this year," Ivanisevic said.

"(Younger players) are here, it's great for tennis, great for the future of tennis. But you still have these two guys battling. This was Novak's home court, and now we go next to Rafa's home court (the French Open)... It's amazing. They really push each other."