Novak Djokovic reaches Australian Open quarter-finals but injury concerns still linger

Defending champion continues to struggle with muscle tear and will face Zverev in the next round

Novak Djokovic defeated Milos Raonic in the Australian Open fourth round but injury could still scupper his title hopes. EPA

Not even a potentially tournament-ending injury could stop Novak Djokovic from booking his place in the Australian Open quarter-finals on Sunday.

Having sustained an abdominal tear in his third round win over American Taylor Fritz, the top seed and defending champion was a serious doubt to even show up for his match against Milos Raonic.

Clearly in discomfort for much of the contest, Djokovic managed to grind out a 7-6, 4-6, 6-1, 6-4 victory over the big-serving Canadian, who himself picked up an injury, to his ankle, during the match inside Rod Laver Arena.

"If it was any other tournament than a Grand Slam I would retire from the tournament, that's for sure," said Djokovic, who becomes just the second player after Roger Federer to win 300 Grand Slam matches.

"But because it's a Grand Slam, I want to give my best alongside my team to try to recover and get on the court."

Djokovic admitted he had not hit a tennis ball in the two days between his third and fourth round matches, instead dedicating all the time he had to his recovery. After a match that lasted four minutes shy of three hours, the big question now is, what sort of shape is the world No 1 going to be in for his quarter-final against Alexander Zverev on Tuesday.

"It's kind of a gamble, that's what the medical team told me. It's really unpredictable," Djokovic said. "It could cause much more damage than it is at the moment, but it also could go in a good direction.

"That's something that I don't know, and I don't think I will know until I stop taking painkillers. But the tricky thing with the painkillers is that they hide what's really happening in there, so you might not feel it, but then the big damage might be done."

Even though he was forced to play four sets, perhaps the positive for Djokovic is that matches against Raonic are rarely energy sapping. The Canadian 14th seed is boom or bust, hitting plenty of aces and winners but just as many errors.

That will not be the case against sixth seed Zverev, who not only represents a step-up in quality but the German's ability to move the ball across the court from the baseline can cause players problems at the best of times, let alone one with a core muscle injury – even if that player is Novak Djokovic.

"Playing against Sascha [Zverev] is a different matchup, there's probably going to be more rallies, gruelling rallies, exhausting, and it's going to be demanding from my side really from back of the court," Djokovic said.

It can often feel like the only player who can stop Djokovic in his tracks his Djokovic himself. While at the US Open last year it was a moment of madness and the subsequent disqualification, in Melbourne injury appears to be the Serb's biggest obstacle in his quest for a record-extending ninth title.

Dominic Thiem did push Djokovic close in the 2020 final but the Austrian third seed will not get another crack at the champion this year after tumbling out in a 6-4, 6-4, 6-0 defeat to Bulgaria's Grigor Dimitrov.

Thiem, who made his major breakthrough in New York, entered the match following an exhausting five-set win over Australian Nick Kyrgios and he lacked sharpness against a dangerous player who has been ranked as high as No 3.

"I feel great. Throughout every season you have one of those matches where you just keep the ball rolling and today was just one of these days," Dimitrov, 29, said.

"I was entirely just trying to focus on what I was doing ... I had to very composed against him. Dominic is an extraordinary player."

Dimitrov will aim to reach his second Australian Open semi-final when he takes on Russian qualifier – and fairytale story of the tournament – Aslan Karatsev.

The world No 114, who is making his Grand Slam debut, looked outclassed during the first two sets of his encounter against Canadian 20th seed Felix Auger-Aliassime. But he turned the match around in remarkable style to seal a 3-6, 1-6, 6-3, 6-3, 6-4 win.

"It was really difficult in the beginning to play with him. He's a really good player and was playing really fast and it took me two sets to find my rhythm," Karatsev said. "I put everything into this match and I'm really happy."