World number one Novak Djokovic won a fifth Australian Open title and his eighth Grand Slam Sunday, grinding down Britain's Andy Murray in four sets to heap more misery on the Scot.

Djokovic won 7-6 (7/5), 6-7 (4/7), 6-3, 6-0 in 3hr 39min to stretch his formidable record on the Melbourne hardcourts to winning five from five finals in eight years.

Only Australian Roy Emerson, who was in the crowd and handed him the trophy, has won more Australian Opens with six in the 1960s.

"I am so privileged and honoured and grateful to be standing here as a champion for the fifth time and to be in the elite group of players with Sir Roy Emerson and Rod Laver and all the legends of our sport," said the Seib.

"It's an honour playing in front of you, thankyou very much. “

"Tough luck tonight, Andy, you are a great competitor, you fight a lot and I want to congratulate your team and wish you all the best for the rest of the season," he said.

The victory means Djokovic stays at world number one on the next ATP rankings when they are released on Monday, with Murray moving to four from his current sixth.

"We have put in a lot of hard work to try and get back in this position after what was a difficult year last year," said Murray, referring to injuries that dogged his 2014 season.

"Unfortunately, I couldn't quite do it tonight but I was a little bit closer than I was a few months ago and I will keep working hard to get there. "

Murray put Djokovic under immediate pressure with three break points in the third game of the opening set, played in cool and windy conditions on Rod Laver Arena.

But the Serb fought back to hold after an almighty 27-stroke rally to set the tone of his victory.