MELBOURNE - An ailing Novak Djokovic said on Saturday that every moment counted now that he was in the “last stage” of his career, after battling past Grigor Dimitrov and into the Australian Open last 16.

The Serb came through a titanic 77-minute first set before taming the Bulgarian 7-6 (9-7), 6-3, 6-4 on Rod Laver Arena, needing treatment twice on his troublesome hamstring.

But there was no such luck for another veteran, Briton Andy Murray, whose brave run ground to a halt against Roberto Bautista Agut, the Spaniard fending off the fatigued former world No. 1 6-1, 6-7 (7-9), 6-3, 6-4.

After back-to-back five-set wins over Matteo Berrettini and Thanasi Kokkinakis, a ragged Murray hung tough against the 24th seed but was gradually worn down over the course of the 3½-hour slog at a floodlit Margaret Court Arena.

Djokovic will face home hope Alex de Minaur for a place in the quarter-finals after the 22nd seed equalled his best result at the tournament by defeating Frenchman Benjamin Bonzi in three sets.

The Serb’s gutsy win inched him nearer to a 10th Australian Open title and record-tying 22 Grand Slam crowns. Winning once again in Melbourne would also return him to world No. 1 for the first time since June.

Now 35, Djokovic said he was savouring each tournament more.

“Every season counts I guess now, when you come to the last stage, the last quarter, of your career,” he said. “Obviously you start appreciating and valuing each tournament more because you might not have a lot left in the tank.

“I’ve been truly fortunate to do what I love, I love the sport, I love competing. It’s been almost 20 years now of professional sport. I can’t be more grateful than I am.”

Victory put him into the last 16 for a 15th time but he was made to work for it, especially with his left hamstring troubling him.

“Every point, every game mattered,” he said. “Obviously I didn’t know how I’m going to feel physically, it was going up and down,” he said.

“It was an incredible battle, three sets over three hours.”

Djokovic aggravated his hamstring during his run to a 92nd title at the Adelaide International this month and has been struggling with it since.

He came into the match without his usual off-day practice session to give his leg as much time as possible to recover.

With his left thigh heavily strapped, the Serb broke immediately and consolidated to take an early grip on the first set.

He was cruising but appeared to feel the injury when moving for a shot at 5-3. He managed to earn three set points, which were saved, but was then broken when serving for the set at 5-4.

Agitated, he complained to the umpire about being given a time violation and was then forced to save two set points, before an epic tiebreak.

He eventually got over the line on his fifth set point after some intense tennis.

He took a medical timeout at the changeover and returned to dial up the pressure and take a break before comfortably seeing out the second set.

With Dimitrov flagging, he turned the screws further by breaking twice early in set three. Despite a mid-set wobble when the Bulgarian clawed back and then more treatment on his leg, Djokovic battled to the finish line.

De Minaur, who is aiming for a first quarter-final at Melbourne Park, now awaits Djokovic after a 7-6 (7-0), 6-2, 6-1 victory.

“These are the matches you want to be playing,” said the Australian. “I’m gonna probably have the best in the world in front of me and I’m ready for the battle.”

Murray’s previous match against Kokkinakis, which ended past four in the morning after nearly five hours of play, left him with little sleep, a bad back and a slew of blisters that needed draining from his feet.

Between points against Bautista Agut, he shuffled around the baseline like a frail senior citizen but when the ball was in play, he threw himself around the court to give the Spaniard a proper scare.

“My feet didn’t feel great. My legs were actually OK ... but I was struggling with my lower back,” the Scot told reporters. “That was affecting my serve and that was really the main thing today.”

With the crowd firmly in his corner, Murray broke Bautista Agut in the first game of the fourth set to raise hopes of levelling the match but he ended up squandering a 2-0 lead before dropping serve in the ninth game.

The spent Scot soon fired a cross-court forehand long to concede match point and netted a weary backhand return to bow out, triggering manic celebrations by Bautista Agut, who will play American Tommy Paul for a place in the quarter-finals.

Bautista Agut knocked Murray out in the opening round of the tournament four years ago, after the tearful Scot said his hip was shot and his career might be over.

It has been a long and punishing road back for the three-time Grand Slam champion since being fitted with a metal hip.

But he was encouraged by his week at Melbourne Park, if disappointed not to reach the second week.

“Lots of mixed emotions, I feel like I gave everything I had to this event, so I’m proud of that,” he said.

“But, yeah, I’m also disappointed because I put loads of work into the beginning of this year and was playing well enough to have a really good run, have a deep run.

“I’m disappointed because I feel like I could have gone quite a bit further.”

At 35 and despite all the aches and pains, Murray’s court movement was impressive. He leaves Melbourne Park without an injury and confident of being ready for his next stop in Rotterdam.

“I felt good about the way that I was playing,” he said.

“It’s more enjoyable for me when I’m playing like that, when I’m coming into a major event and really believing that I can do some damage.” AFP