Rafael Nadal suffered a remarkable collapse to exit the Australian Open at the quarter-final stage despite earlier leading Stefanos Tsitsipas by two sets.

Only once in Nadal's grand slam career had he previously let a two-set lead slip and such a slump appeared entirely improbable as he dominated Tsitsipas on Rod Laver Arena.

But the 20-time major champion, chasing a record-breaking 21st title, struggled to recover his momentum after dropping a set for the first time in the tournament when the third went to a tie-break.

The courageous Tsitsipas grew in confidence and landed a momentous second career win over Nadal to reach a third slam semi after a four-hour 3-6 2-6 7-6 (7-4) 6-4 7-5 epic.

Daniil Medvedev secured his first Australian Open semi-final berth after continuing his domination of fellow Russian Andrey Rublev in straight sets.

Medvedev starred in the Melbourne heat as countryman Rublev faded, winning 7-5 6-3 6-2 on Wednesday to reach his third grand slam semi-final, equalling Alex Metreveli for third place on the Open Era list for most major semis by a Russian man.

World number four Medvedev – the fifth Russian man to reach the Australian Open semis in the Open Era, after Metreveli (1972), Yevgeny Kafelnikov (1999-2000), Marat Safin (2002, 2004-05) and Aslan Karatsev (2021) – will face either 20-time slam champion Rafael Nadal or Stefanos Tsitsipas for a spot in the decider.

Medvedev and Rublev were meeting for the fourth time on the ATP Tour – their second in a grand slam quarter-final, with the former winning all previous meetings in straight sets. 

Runner-up at the 2019 US Open, Medvedev had a glimpse on Rublev's serve before breaking in the sixth game for a 4-2 lead, only to hand the break straight back to his countryman.

The tense battle continued behind closed doors on Rod Laver Arena as a tie-break loomed large, until Medvedev closed out the 46-minute set on Rublev's serve.

It was a similar theme in the second set, with little separating the two Russian hopefuls under the warm Melbourne sun.

Rublev, who won five ATP Tour titles last year – more than any other player, while earning a joint-best 41 wins in 2020 alongside world number one Novak Djokovic, continued to take the match to Medvedev.

Three break-point chances came Rublev's way in the seventh game, but he was unable to convert and Medvedev made him pay as the world number four broke the very next game before earning a two-sets-to-love lead.

Rublev – eyeing his first slam semi – deteriorated in the warm conditions, often hunched over between points while trying to keep cool in the shade, as Medvedev cruised.

Data Slam: Medvedev extends streak
There is no stopping Medvedev at the moment after he extended his winning streak to 19 matches, already a career-best run – dating back to the Vienna Open last October.

WINNERS/UNFORCED ERRORS
Medvedev – 30/33
Rublev – 20/39

ACES/DOUBLE FAULTS
Medvedev – 14/4
Rublev – 8/3

BREAK POINTS WON
Medvedev – 5/11
Rublev – 1/5

Australian Open fans are set to return to Melbourne Park from Thursday after the Victorian government confirmed the lifting of restrictions following a five-day lockdown amid the coronavirus pandemic.

While the number of supporters set to attend remains unknown, fans will be back in their seats for the beginning of the Australian Open semi-finals, with record-chasing Serena Williams set to face three-time grand slam champion Naomi Osaka in Melbourne.

Defending men's champion Novak Djokovic will play the tournament’s surprise package, Russian qualifier Aslan Karatsev - who is the first player to reach a semi-final on their grand slam debut.

Djokovic was on court when the lockdown came into effect last Friday, with the five-day "circuit-breaker" designed to control an outbreak of the UK coronavirus strain.

Part of the third round, the fourth round and quarter-finals of singles action were played behind closed doors after a series of outbreaks in Victoria.

The state has recorded 12 more active cases since the lockdown was implemented but, with none discovered in the past 24 hours, Victorian premier Daniel Andrews announced restrictions will be eased.

"I'm very, very pleased to announce that the restrictions will come off, almost all of them, at midnight tonight," Andrews told reporters on Wednesday.

"From 11:59pm [Wednesday local time], the restrictions will be dropped [but] masks will be required indoors and outdoors when you can't socially distance."

The stage-four restrictions meant residents could not leave their homes for any other reason than work, shopping for groceries, exercise or the giving or receiving of medial care.

This year's delayed Australian Open has had crowds capped at 30,000 per day with original COVID-19 restrictions, but new limits are yet to be determined for the rest of the tournament.

"There will be meetings this afternoon [to determine] what is a safe number," Andrews said.

"They already were reduced, they may have to be reduced further, but that matter will be resolved in the next few hours."

Aslan Karatsev said finding stability off the court has helped him become the revelation of this year's Australian Open after the qualifier marched on to the semi-finals.

The Russian became the first qualifier to reach the last four of a major since Vladimir Voltchkov, famously in borrowed shorts, did so in 2000 at Wimbledon.

It was Pete Sampras who eventually blew away Voltchkov's threat at the All England Club on his way to another title.

And it turns out there is a connection between Karatsev and Voltchkov, with both men now calling Minsk their home.

But whereas Voltchkov is Minsk born and bred, Karatsev has taken a roundabout route to setting down roots in the capital of Belarus.

He explained on Tuesday how he was born in the Russian city of Vladikavkaz before moving as a toddler to Israel with his family and living there until the age of 12, when he and his father returned to Russia, spending time in the city of Taganrog.

Tennis took him to training bases in Moscow, then Halle in Germany, Barcelona, and finally Minsk.

It is in Minsk that Karatsev has linked up with former ATP professional Yahor Yatsyk, a man only one year his senior but already settling into coaching.

As Grigor Dimitrov succumbed to injury and slid to a four-set defeat against Karatsev on Tuesday, the unlikely figure in the final four reflected on his long road to this point.

"Yes, I was moving I would say too much," Karatsev said of his nomadic existence.

"In the end I found a coach, Yahor Yatsyk, and this is the right guy for me. He's helped me a lot, more the mental part, and then of course there is the technical stuff as well.

"I like to work with him. We're living in Minsk. We're practicing there."

Karatsev is the lowest-ranked man to reach a grand slam semi-final since Goran Ivanisevic, who won Wimbledon in 2001 on a wildcard entry while ranked 125th in the world.

His charge through the draw makes him only the second qualifier to advance to the Australian Open last four, after Bob Giltinan in December 1977.

"Of course it's amazing that I passed to the semi-finals from qualifying," Karatsev said. "I'm just trying to enjoy the moment and not thinking about that too much and playing from round to round."

He and Yatsyk set the goal of reaching the top 100, which Karatsev had not managed before getting to Melbourne.

Before this fortnight he stood at 114th in the rankings, but he will hurtle to a double-digit ranking next week.

"I think the key is to find the right team, the right coach that I found. I was really lucky to find him," Karatsev said.

"We just met in one tournament. We were saying, 'Okay, let's try to work together', and it's really a big luck that we started to work together and I have a good team around me."

Before he encountered Yatsyk, who as a player did not crack the top 1,000 in singles, Karatsev had a brief moment when he wondered if he might not make the grade.

"There was a time when I was injured that was a difficult time for me because I recovered after the injury, and then 2017 started, and I started to play again, and again I felt the knee," Karatsev said. "I said, 'Whoa.' I quit again for two and a half months, almost three, and I think this is the most difficult part."

Aslan Karatsev's Cinderella story and historic run continued after sensationally reaching the Australian Open semi-finals as Grigor Dimitrov struggled dramatically with injury on Tuesday.

Former world number three Dimitrov won the opening set and was on track to move through in Melbourne, but he faded alarmingly due to a lower back problem.

Karatsev capitalised to oust his much-more fancied opponent – who was barely able to walk afterwards – 2-6 6-4 6-1 6-2 on Rod Laver Arena, the Russian qualifier and world number 114 becoming the first man in the Open Era to reach the semi-finals on his grand slam debut.

The unheralded 27-year-old also became just the second qualifier to advance to the Australian Open last four after Bob Giltinan in December 1977 as defending champion Novak Djokovic or Alexander Zverev await.

Dimitrov was aiming to reach his second Australian Open semi-final and the final four of a slam for the fourth time in his career, and the Bulgarian star started well.

After being broken in the third game, 18th seed Dimitrov put the set back on serve immediately as he took control of proceedings.

Dimitrov fired down four aces, won 82 per cent of his first serves, hit six winners and made just five unforced errors, while Karatsev's unforced-error count hit 19.

But just as Dimitrov – who had not dropped a set en route to the quarters – looked like the man to beat, he wilted in remarkable scenes as Karatsev won the second set to level the match.

Dimitrov's first-serve winners dipped to 69 per cent – his second serve extremely problematic – while his unforced errors grew to 15 in the second set – and Karatsev took advantage.

The third set was a write-off for Dimitrov, who headed to the locker room for medical treatment after Karatsev cruised to a two-sets-to-love lead.

There were remarkable scenes in the third set, Dimitrov virtually conceding as he was unable to keep up with Karatsev due to the injury.

Dimitrov, who only won 12 points in the third set as he was unable to keep up with Karatsev or generate any power on his serve, emerged for the fourth set but, while he tried to will himself on, it only delayed the inevitable in sad scenes.

Data Slam: Karatsev joins Russian club
Karatsev became the fourth Russian man to reach the Australian Open semis in the Open Era, after Aleksandar Metreveli  (1972),  Yevgeny  Kafelnikov  (1999-2000)  and  Marat  Safin  (2002, 2004-05). He is also the lowest-ranked man to reach the semi-finals of a major since Goran Ivanisevic (125) at Wimbledon in 2001.

WINNERS/UNFORCED ERRORS
Dimitrov – 21/34
Karatsev – 34/44

ACES/DOUBLE FAULTS
Dimitrov – 9/7
Karatsev – 9/6

BREAK POINTS WON
Dimitrov – 4/14
Karatsev – 8/11 

Former world number one and two-time grand slam champion Yevgeny Kafelnikov believes it is "inevitable" that a Russian player will claim major success as the country's male trio flourish at the Australian Open.

For the first time in the Open Era, three Russian men advanced to the quarter-finals of a slam thanks to star Daniil Medvedev, Andrey Rublev and qualifier Aslan Karatsev in Melbourne.

World number four Medvedev – the 2019 US Open runner-up – will face countryman Rublev in the Melbourne Park quarters as Karatsev meets Grigor Dimitrov for a spot in the semi-finals.

Not since Marat Safin at the 2005 Australian Open has a Russian male won a slam, but Kafelnikov is excited about the future.

"We all know that it's inevitable that they're going to win a slam," Kafelnikov, who was the first Russian man to earn a grand slam singles championship via the 1996 French Open before reigning supreme at Wimbledon three years later, told ATPTour.com.

"It's a question of when and where."

Kafelnikov added: "It was really expected that two of them got to where they are. The third one is a big surprise, but a very happy surprise. I'm very happy for Aslan, finally getting his breakthrough.

"He's going to play a lot of tournaments now without any pressure for the remainder of the 2021 season in terms of getting into the main draws and a big pay cheque will also be a huge boost for him. I'm really happy for him."

Kafelnikov, who won 26 singles titles, continued: "To be honest, I would be happy if one of those guys or even both of them surpass me in terms of number of titles and weeks at number one in the world.

"I'd be happy. I'm not going to be jealous about it. My career was very successful, and hopefully they will have even better [careers]."

Rafael Nadal insisted he is not "obsessed" in his quest for further grand slam glory after the 20-time major champion moved through to the Australian Open quarter-finals. 

Nadal advanced to the last eight of the tournament for the 13th time in his illustrious career following Monday's dominant 6-3 6-4 6-2 victory over 16th seed Fabio Fognini.

World number two Nadal is bidding to claim a record 21st slam crown, while the Spanish star is also looking to become the first man in the Open Era to win each of the four majors twice.

As Nadal looks ahead to a showdown with fifth seed Stefanos Tsitsipas, he discussed his motivations, having won everything on offer on the ATP Tour.

"I play tennis. I like tennis," the 34-year-old said. "I like what I am doing. That's the main thing. 

"Of course I am very motivated to win grand slams and to play in the most important events of the year. No doubt about that.

"The only thing that I said is I have never been obsessed to try to be the best or to try to – no, I just did my way. That worked for me.

"I think the ambition is important, to have an ambition, but a healthy ambition. If you have too much ambition then you can be frustrated when you are not able to achieve all the things that you wanted.

"I never approached the sport and my career that way. That's it. I enjoy, I give my best always. I try to compete at my highest standards every day. Sometimes the highest standards are 60 per cent, sometimes they are 100 per cent. But I just try to give my best throughout my career, and that's it.

"For me the main thing is come back home with personal satisfaction that you gave it everything. That's what gives me happiness and makes me stay calm."

Nadal was under an injury cloud heading into the year's first grand slam due to a back problem which forced him to sit out Spain's ATP Cup campaign in Melbourne.

But the 2009 Australian Open champion has looked comfortable at Melbourne Park, where he is yet to drop a set.

"I played first set without a doubt [against Fognini] has been my best level in the tournament," Nadal said. "It's normal, too, because I was able to practice for two days in a row. That makes an important difference. 

"But at the same time, it's important to find positive feelings now. My physical condition needs to keep improving. But I think this match helps, too.

"I was not able to practice the proper way for the last 19 days, but yesterday [Sunday] I started again to increase the amount of work on the practice, and today has been a positive victory with some long points, so that helps for the next match."

Rafael Nadal's bid to win a record 21st grand slam title remains on track, while there is a distinctly Russian flavour to the quarter-final line-up at the Australian Open.

World number two Nadal eased past Italian 16th seed Fabio Fognini behind closed doors at Melbourne Park in sunny and warm conditions on Monday.

Daniil Medvedev and Andrey Rublev ensured Russia made history en route to the quarters in Melbourne.

FAMILIAR TERRITORY FOR NADAL

Nadal reached the Australian Open quarter-finals for the 13th time in his career after outclassing Fognini 6-3 6-4 6-2 on Rod Laver Arena.

Stuck on 20 slam championships alongside Roger Federer, who is absent in Melbourne, Nadal is also looking to become the first man in the Open Era to win each of the four majors twice.

The 2009 Australian Open champion was too good for Fognini as Nadal continued his fine run of not dropping a set en route to the last eight in 2021.

Only at the French Open, where he is a 13-time champion, has Nadal reached the quarter-finals more often (14) than at the Australian Open. Federer (15) and John Newcombe (14) are the only men to have reached more Australian Open quarter-finals.

Nadal, who hit 24 winners against Fognini, will face fifth seed Stefanos Tsitsipas for a place in the semi-final after ninth seed Matteo Berrettini withdrew with an abdominal strain before Monday's showdown.

HISTORY FOR RUSSIA​

For the first time in the Open Era, three Russian men have advanced to the quarter-finals of a slam.

Medvedev – the fourth seed – and Rublev joined countryman Aslan Karatsev in the last eight following their respective triumphs on Monday.

Runner-up at the 2019 US Open, Medvedev made light work of American Mackenzie McDonald 6-4 6-2 6-3, extending his winning streak to 18 matches as he reached his maiden Australian Open quarter-final.

"It's an exciting moment to be in the quarters in Australia for the first time. That's a great achievement for me," Medvedev said.

"I want more all the time, but step by step. So this is amazing … I finished at 1.30 [hours], which is important in the later stages of the grand slams, to make fast matches."

It will be an all-Russian affair in the quarters after seventh seed Rublev benefited from a walkover.

Rublev was leading 6-2 7-6 (7-3) when Norway's Casper Ruud retired on Margaret Court Arena.

"At least one of us will be in the semi-finals. So it's good news but yeah, it's going to be a tough match," said Rublev, who featured in last year's French Open quarter-finals.

"Last time he beat me in the quarters in the US Open. So now we're in the quarters in the Australian Open, so we'll see what's going to happen."

Rafael Nadal reached the Australian Open quarter-finals for the 13th time in his career with a straight-sets win over Fabio Fognini.

The Spanish star again looked in strong form in a 6-3 6-4 6-2 victory over Italian 16th seed Fognini behind closed doors on Rod Laver Arena on Monday.

Nadal, who is aiming to win a men's record 21st grand slam title in Melbourne, is yet to drop a set at the year's first major and beat Fognini for the 13th time in 17 meetings.

The world number two will face either Stefanos Tsitsipas or Matteo Berrettini in the last eight.

Nadal gave up an early break lead against Fognini but a powerful forehand return led to another and a 4-2 lead.

Despite serving at just 42 per cent, Nadal closed out the opening set.

Fognini was unable to consolidate a break lead in the second set, having led 4-2, before Nadal recovered from 0-40 down to hold in the eighth game.

That would prove a decisive hold, Fognini blasting a ball into the stands after netting a volley to give Nadal a break point, converted when a forehand went wide before the Spaniard secured the set.

Fognini handed Nadal his only loss from two-sets-to-love up at a grand slam at the US Open in 2015, but a break for 2-1 in the third saw the latter end any chances of a repeat on his way to a convincing win.

Data Slam: Nadal's fine Australian Open record
Only at the French Open, where he is a 13-time champion, has Nadal reached the quarter-finals more often (14) than at the Australian Open. Roger Federer (15) and John Newcombe (14) are the only men to have reached more Australian Open quarter-finals.

WINNERS/UNFORCED ERRORS
Nadal – 24/20
Fognini – 32/35

ACES/DOUBLE FAULTS
Nadal – 6/3
Fognini – 7/3

BREAK POINTS WON
Nadal – 6/19
Fognini – 2/6

Novak Djokovic fought into the quarter-finals of the Australian Open despite concerns over a muscle injury, seeing off Milos Raonic in four sets.

Djokovic's hopes of defending his title appeared to be in doubt when he said he had a "muscle tear" and was unsure whether he would play the fourth-round clash.

But his history of dominance over Raonic was perhaps a motivating factor in him taking to the court and he stretched his head to head lead to 12-0 with his 300th grand slam win, becoming only the second player in history to reach the landmark.

He did not have it all his own way, a spirited Raonic levelling matters in the second set after losing the first on a tie-break.

However, Djokovic was in control thereafter, progressing 7-6 (7-4) 4-6 6-1 6-4, though a last-eight meeting with Alexander Zverev may prove a sterner test.

Djokovic made it eight wins in nine in tie-breaks with Raonic to take the first set and things looked bleak for the Canadian when he received treatment on his foot in the second set.

But that break proved just the tonic for Raonic as he went on to win a set against Djokovic for the first time in four grand slam meetings.

Yet the tide turned emphatically back in Djokovic's favour in the third – the Serbian winning five straight games to move into a 2-1 lead.

His success came through a familiar strategy against a player of Raonic's power on serve.

Djokovic wasted few opportunities to punish the second serve and consistently took Raonic out of his comfort zone by forcing him into long rallies.

Raonic, to his credit, did save four break points in the fourth set but the dam finally burst and he could not prevent Djokovic from snatching the fifth chance that came his way, the world number one ensuring there was to be no shock as he reached another milestone in a remarkable career.

Data Slam: Djokovic's delightful dozen

Djokovic is through to a 12th quarter-final in Melbourne, the eight-time winner last failing to reach the stage in 2018, when he lost to Hyeon Chung.

WINNERS/UNFORCED ERRORS
Djokovic – 41/25
Raonic – 50/35

ACES/DOUBLE FAULTS
Djokovic – 10/3
Raonic – 26/3

BREAK POINTS WON
Djokovic – 3/11
Raonic – 1/3

Dominic Thiem's bid to reach back-to-back Australian Open finals was dashed by Grigor Dimitrov as the US Open champion surprisingly crashed out in the round of 16.

Thiem lost a thrilling final to Novak Djokovic in last year's Melbourne Park decider before breaking through for his maiden grand slam title at Flushing Meadows later in 2020.

But Thiem failed to secure another second-week berth in Melbourne, where the third seed was stunned 6-4 6-4 6-0 by former world number three Dimitrov on Sunday.

Thiem was aiming to reach the Australian Open quarter-finals for the second time and become the second Austrian man to feature in the quarters in Melbourne on multiple occasions after Thomas Muster (1989, 1994 and 1997).

The 27-year-old Thiem was also bidding to reach his ninth slam quarter-final and equal Muster's record for most major last-eight appearances by any Austrian – male or female.

However, Thiem – who rallied from two-sets-to-love down to top Nick Kyrgios in the previous round – was no match for Dimitrov behind closed doors on Rod Laver Arena amid a coronavirus lockdown in Victoria.

Both players hit 25 winners, but Dimitrov only tallied 18 unforced errors to Thiem's 41 following just over two hours on court.

Dimitrov progressed to his fourth Australian Open quarter-final, extending his record for most last-eight appearances at Melbourne Park by a Bulgarian player – man or woman.

An Australian Open semi-finalist in 2017, Dimitrov will now contest his sixth grand slam quarter-final – the 29-year-old is third for most quarter-final appearances by a Bulgarian player, behind Manuela Maleeva (nine) and Katerina Maleeva (seven).

Novak Djokovic insists there is a real danger he may withdraw from the Australian Open, with an ultrasound on an abdominal injury planned for Saturday.

The eight-time champion at Melbourne Park pulled off a dramatic five-set win over American Taylor Fritz to reach round four, but it came at what could prove a high cost.

After battling through two tight sets to forge ahead in the match, Djokovic was jolted early in the third by a sudden "tear", as he put it.

Although painkillers allowed him to continue and fend off a Fritz comeback, the world number one might be advised by doctors that his race in Australia is run for this year.

He is due to face Milos Raonic on Sunday in round four, and the Canadian is a player that Djokovic holds an 11-0 winning career record against. This time Raonic could be gifted a walkover.

Explaining the injury blow, and what comes next, Djokovic said: "Everything was working fine for me, and then beginning of the third set I made this quick move on the return going to the forehand, rotating there, and I just felt a tear, I felt something happen.

"Went out for medical timeout when I was tested, evaluated. I have huge pain, I took the highest dose of anti-inflammatories possible.

"It did kick in end of fourth, beginning of the fifth when I actually started to move and I could actually start to rally with him from back of the court.

"Until that moment, it was only serve for me and kind of hoping and praying that I'm going to get an easy ball after my serve so I could just go for it. That's what I've done.

"I honestly don't know how I won this match. I'm very proud, at the same time sad and worried, because it's definitely something serious happening with my injury.

"I don't have much time to recover for the next match. Definitely not training tomorrow [Saturday]."

The 33-year-old Serbian would not want to risk worsening the problem, given he has plenty to play for over the rest of the year.

However, he is chasing grand slam success wherever he can get it, given he trails Roger Federer and Rafael Nadal by three on the all-time list.

Djokovic's disqualification for hitting a ball that struck a line judge at the US Open last year was followed by defeat to Nadal in the French Open final, and now his luck may be out again.

Once the tests take place on Saturday, there should be a greater sense of clarity in Djokovic's mind.

Setting the scene for what should have been a relaxed day of practice but is now a crucial day in his championship, Djokovic stressed he hoped to be able to continue.

He said of his Saturday plan: "I'm coming here to evaluate more with the doctor and medical team, and do some ultrasound and understand what's really going on so that the doctor and medical team can prescribe best possible treatment and the only possible treatment that I could even have the slightest chance to go out in less than 48 hours."

Novak Djokovic is unsure whether he will be able to play in the Australian Open fourth round after struggling with an abdominal injury in his five-set win over Taylor Fritz.

The world number one survived a huge injury scare to get past Fritz in the third round, winning 7-6 (7-1) 6-4 3-6 4-6 6-2 on Rod Laver Arena.

Eight-time Australian Open champion Djokovic appeared to injure his abdominal region during the third set.

It was a match which started on Friday in front of a crowd and finished on Saturday without fans as Victoria went into a five-day lockdown.

Fritz appeared set to reach the fourth round of a major for the first time in his career, but Djokovic suddenly came to life in the fifth set.

Next up for Djokovic is Milos Raonic, who he has beaten in all 11 of their meetings, on Sunday.

But the Serbian is concerned by his injury and was unable to commit to saying he would be able to take to the court.

"I really don't know," Djokovic said when asked for his thoughts about facing Raonic.

"Right now, I know it's a tear, definitely, of the muscle so I don't know if I'll manage to recover from that in less than two days.

"I don't know. I don't know. I don't know if I'm going to step out on the court or not.

"I am very proud of this achievement. Let's see what happens."

Djokovic felt for American Fritz after his brave defeat and discussed what he had gone through during a contest lasting three hours and 25 minutes.

He continued: "I want to congratulate Taylor for a great fight. I'm sorry that he lost the match obviously.

"I don't know. I just tried to stay in there and I was hopeful that whatever is happening there is going to feel better.

"Towards the end of the fourth it started to feel better, third and fourth set I just served and couldn't do much on the return.

"I was just going for my shots, was hitting two first serves and it worked, it worked well.

"This is definitely one of the more special wins in my life. It doesn't matter what round it is and against who it is.

"Under these kinds of circumstances, to pull this through is definitely something I'll remember forever."

Novak Djokovic survived a huge injury scare to get past Taylor Fritz in the Australian Open third round - but his title defence could be in ruins.

The world number one and eight-time champion in Melbourne edged Fritz 7-6 (7-1) 6-4 3-6 4-6 6-2 on Rod Laver Arena.

But the 17-time grand slam winner appeared to injure his abdominal region during the third set of the contest, which started on Friday in front of a crowd and finished on Saturday without fans as Victoria went into a five-day lockdown due to coronavirus concerns.

Fritz appeared set to reach the fourth round for the first time in his major career, but Djokovic suddenly came to life in the fifth set.

Next up for Djokovic is Milos Raonic, who he has beaten in all 11 of their meetings, but whether the Serbian is fit enough to play remains to be seen.

Djokovic told Eurosport he suspected he had suffered a torn muscle and that it was "in the clouds" whether he would be able to continue in the tournament.

Djokovic broke for 3-1 against Fritz and crucially dug himself out of a 15-40 hole in the seventh game, but a forehand into the net saw him fail to serve out the set.

Yet Djokovic was close to flawless in the tie-break, winning the first six points before closing it out, and then breaking to begin the second set.

That spurred Djokovic to win the second before the drama followed.

He took a medical timeout after the third game of the third set and then repeatedly required treatment on his abdominal region.

The injury seemed to be bothering Djokovic, who was broken after sending a forehand long in the eighth game, and Fritz closed out the set.

A struggling Djokovic was broken again in the third game of the fourth set before fans were forced to leave Rod Laver Arena ahead of restrictions being introduced in Victoria, but Fritz levelled the match.

Djokovic looked far healthier to begin the final set and he broke for 4-2 with a brilliant forehand winner after a baseline exchange, winning four straight games on his way to a post-midnight victory.

Data Slam: Djokovic's American dominance continues … just
Djokovic extended his winning streak against Americans at tour level to 17 matches. His last loss to an American opponent came against Sam Querrey at Wimbledon in 2016.

WINNERS/UNFORCED ERRORS
Djokovic – 52/53
Fritz – 62/45

ACES/DOUBLE FAULTS
Djokovic – 15/5
Fritz – 24/1

BREAK POINTS WON
Djokovic – 4/9
Fritz – 3/12