MELBOURNE, Australia (AFP) — World number one Novak Djokovic won a fifth Australian Open title and his eighth Grand Slam yesterday, grinding down Andy Murray in four gruelling sets to heap more misery on the luckless Scot.

The Serb won 7-6 (7/5), 6-7 (4/7), 6-3, 6-0 in three hours and 39 minutes to stretch his formidable record on the Melbourne hardcourts to winning five from five finals in eight years.

Only Australian Roy Emerson, who presented him with the trophy, has won more Australian Opens with six in the 1960s.

Djokovic has now beaten Murray in three of his four Australian final losses following earlier wins in 2011 and 2013, although the Scot mastered him in his two major triumphs at the 2012 US Open and 2013 Wimbledon.

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

“Two and a half hours the first two sets. Very physical. Very exhausting,” Djokovic said.

“We both went through some tough moments physically. You could see that I had a crisis end of the second, beginning of the third.

“I just felt very exhausted and I needed some time to regroup and recharge and get back on track. That’s what I’ve done.”

Djokovic said his latest win was all the more important given his new status as a husband and a father.

“I think it has deeper meaning, more intrinsic value now to my life because I’m a father and a husband,” he said.

Dejected Murray admitted he couldn’t match his rival in the fourth and final set.

“I had opportunities in the first three sets. Then the fourth set, he was just ripping everything,” he said.

“The returns he was hitting on the baseline, once he got up a break, he just loosened up and was just going for his shots. I couldn’t recover.”

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 and an ace.

Djokovic struck in the next game, breaking Murray to take an early 3-1 lead.

It was hard-fought tennis, and the Scot worked his way back by breaking his rival on his third break point in the seventh game.

Djokovic jammed the thumb of his serving hand when he slipped chasing a low volley, and needed treatment at the next changeover.

It seemed to bother him briefly only and he broke the Scot a second time before being broken back as he served for the opening set, taking it to a tiebreaker.

The top seed trailed 2-4 in the tiebreaker, but then rattled off five of the next six points to claim the opening set in 72 minutes.

Undeterred, Murray broke for a 2-0 lead in the second set before Djokovic hit back with a double break.

The final was then interrupted by a security scare for five minutes when political activists unfurled a banner in support of refugees.

Two of them jumped on court, with security guards ringing both players, as at least four protestors were escorted out of the stadium.

The stoppage worked in Murray’s favour as he broke Djokovic’s service to level the set at 4-4. It went to a second tiebreak in which Murray prevailed 7-4 to level the contest.

Djokovic admitted the protest distracted him.

“The interruption on the court happened and I lost my concentration and Andy started coming into the match, and two and half hours and two sets it took a toll of our bodies,” he said.

“I didn’t want to show him that I was going through some tough physical moments.”

Djokovic suffered an immediate let-down in the third set, dropping his opening service, but he stormed back with a double break to edge in front two sets to one.

Fired-up, the top seed then split the final set wide open, racing through it against a spent Murray with a triple break to surge to victory.