Jamie Murray has questioned why Novak Djokovic was granted special dispensation to compete at the Australian Open.

Seven-times grand slam doubles champion Murray was asked about the decision to grant Djokovic a medical exemption for the year's first grand slam tournament at Melbourne Park.

Players have been obliged to either prove they are vaccinated against COVID-19 or apply for an exemption, which tournament organisers said involved a "rigorous" process to prove eligibility.

World number one Djokovic is a nine-time Australian Open men's singles champion, yet it was unclear until Tuesday whether he would be allowed to play the event this year.

There has been early backlash to the decision to clear him, with Melbourne having been hit by multiple lockdowns during the pandemic and many believing only vaccinated players should be playing.

Murray, brother of Djokovic's long-time friend and rival Andy Murray, spoke after the Serbian was permitted to travel into Australia and said he doubted he would get the same treatment.

Asked about the situation in an ATP Cup news conference, Jamie Murray said: "I don't know what to say about that really. I think if it was me that wasn't vaccinated, I wouldn't be getting an exemption.

"But well done to him for getting cleared to come to Australia and compete."

Djokovic may wish to elaborate further on the factors behind him being given the green light to travel into the state of Victoria, and will doubtless face media questions about the situation once he arrives.

However, the 20-time grand slam winner has been unwilling to disclose his vaccination status until now, which suggests there is little prospect of him offering further medical insight at this stage.

Asked if he felt it was not a fair decision to exempt Djokovic, Jamie Murray added: "Whatever you want to say, that's the situation."

Murray, 35, was interrupted at that point by Great Britain captain Liam Broady, who said: "At the end of the day, you have to trust he has a valid reason for the medical exemption, that's all you can say about it really, isn't it."

However, Broady had no doubt Djokovic would play the Australian Open, which begins on January 17, and claimed it was a foregone conclusion.

In an Instagram story, Broady posted a screenshot of Djokovic's announcement, adding the remark: "The second AO announced there would be exemptions 8 weeks ago we all knew."

Andy Murray stumbled out of the Melbourne Summer Set tournament after a first-round defeat to Argentinian Facundo Bagnis.

In his opening ATP Tour match of the year, three-time grand slam winner Murray slipped up 6-3 5-7 6-3 against Bagnis, a player who began the year with a 30-59 win-loss career record.

Left-hander Bagnis rose to the occasion on Rod Laver Arena to earn the scalp of the former world number one.

Murray, down at 134th in the rankings after another injury-hit year, is looking to make headway on that front in 2022 under new coach Jan de Witt, so that he can avoid having to take wildcards into tournaments.

He was allowed into this tournament by that back-door route, and has also been confirmed for an Australian Open wildcard, but the Scot could not find the form that saw him beat Rafael Nadal at an exhibition event in Abu Dhabi in late December.

Bagnis said of his win: "In the beginning it was a pleasure to play against Andy and right now to beat him is amazing. I'm really happy."

He added, according to the tournament website: "Yesterday, I came to see the stadium, to see it all around because the atmosphere is different when you play on any court outside… I enjoyed it a lot. It was so good for me."

Nadal was also back in action on Tuesday, playing his first match on the main tour since August as he teamed up with fellow Spaniard Jaume Munar for a doubles win.

A foot injury meant Nadal's 2021 season ended early, but he warmed up for singles tests that lie ahead by joining Munar for a 6-3 3-6 10-4 win over Argentinians Sebastian Baez and Tomas Martin Etcheverry.

At the Adelaide International 1 tournament, there was a notable first-round win on Tuesday for Australian Thanasi Kokkinakis, who saw off compatriot John Millman 6-4 6-3.

Kokkinakis, a major talent as a youngster, is battling to reassert himself on tour after injury troubles, and beating Millman put his name up in lights for at least one day.

He reflected afterwards on the battle it has taken so far, with last year spent largely living out of a suitcase on the second-tier Challenger Tour.

"It was a gruelling year travelling," said Kokkinakis. "I've played a couple of times [in Adelaide] but just in exhibitions, so to play a real meaningful tournament and beat such a quality opponent, a proven veteran like Johnny, means a lot. I played great, and the support was great, so I'm really happy."

Novak Djokovic went through "rigorous" checks before being handed a medical exemption to compete at the Australian Open, tournament chiefs insisted.

A wave of criticism followed Djokovic's announcement that he was on his way to Melbourne for the season's first grand slam tournament.

The Serbian has not directly addressed whether he has been vaccinated against COVID-19, but players who compete at Melbourne Park either require proof they have been jabbed or an exemption.

He has spoken openly and critically about vaccine mandates, insisting there should be freedom of choice in all walks of life.

Many Australians on social media spoke out against the decision to welcome Djokovic into the country, predicting he could face a frosty reception while the country battles surging cases of the Omicron variant.

Djokovic will be bidding to win a 10th Australian Open title and a record 21st singles grand slam, more than any man in history.

The 34-year-old had his bags packed and was awaiting a flight at an airport when he broke the news of his trip to Australia on Tuesday.

Australian Open chiefs confirmed he had been granted permission to play, saying in a statement: "Novak Djokovic will compete at the Australian Open and is on his way to Australia.

"Djokovic applied for a medical exemption which was granted followting a rigorous review process involving two separate independent panels of medical experts. One of those was the independent medical exemption review panel appointed by the Victorian Department of Health."

There has been no detail given of why Djokovic qualified for an exemption, and unless he is willing to disclose personal medical information it is set to remain that way.

Australian Open tournament director Craig Tiley said it remained the case that all involved with the tournament, from fans through to players, must be fully vaccinated or have an exemption permission allowing them to attend.

Tiley said: "Fair and independent protocols were established for assessing medical exemption applications that will enable us to ensure Australian Open 2022 is safe and enjoyable for everyone.

"Central to this process was that the decisions were made by independent medical experts and that every applicant was given due consideration."

Explaining the process of securing exemptions, the Australian Open indicated in its statement that Djokovic would not have been treated as a special case.

It pointed out that a government-appointed panel assessed all cases that got past the first stage of checks, and that "the process included the redaction of personal information to ensure privacy for all applicants".

This should mean Djokovic was not identifiable to those making the crucial decisions about whether he should be allowed to take part.

"The multi-step independent review process was designed to ensure the safety of everyone at the Australian Open," the tournament statement added.

Novak Djokovic has announced he will play at the Australian Open, revealing he has been given "exemption permission" to compete.

The world number one and nine-time champion in Melbourne has not declared whether he has been vaccinated against the COVID-19 virus.

Australia has stringent rules about who should be allowed to enter the country, with tennis players needing to be either vaccinated or hold a medical exemption in order to play the grand slam tournament.

Serbian superstar Djokovic wrote on Instagram on Tuesday: "I’ve spent fantastic quality time with my loved ones over the break and today I'm heading Down Under with an exemption permission. Let's go 2022!!"

Djokovic's message was accompanied by a picture of him at an airport, with a tennis racquet bag atop his luggage on a trolley, indicating he was ready to board his flight to Australia.

He told his followers: "Happy New Year, everybody! Wishing you all health, love, and happiness in every present moment and may you feel love and respect towards all beings on this wonderful planet."

Australian Open tournament director Craig Tiley said on Sunday he expected defending champion Djokovic's status for the event to become clear within days. The grounds for Djokovic receiving an exemption have yet to be disclosed, and it is unclear whether they will ever be made public.

The 20-time grand slam winner withdrew from the ATP Cup in Sydney last week, begging questions of whether he would head to Australia at all, but now that appears to have been cleared up.

Djokovic has steadfastly refused to disclose whether he has been jabbed. His declaration that he has been given an exemption points to him not having been vaccinated.

The 34-year-old won in Melbourne last February and followed up by triumphing at the French Open and Wimbledon to join Rafael Nadal and Roger Federer on 20 major titles.

Djokovic will be attempting to seize the outright lead by capturing a 21st slam, with the Australian Open running from January 17-30 at Melbourne Park.

He was on the same mission at the US Open but lost out to Daniil Medvedev in the New York final in September, as the Russian landed his first grand slam title at Flushing Meadows.

Medvedev was the man Djokovic beat in last year's Australian Open final, and is again expected to be a major challenger this time around.

Novak Djokovic has announced he will play at the Australian Open, revealing he has been given "exemption permission" to compete.

The world number one and nine-time champion in Melbourne has not declared whether he has been vaccinated against the COVID-19 virus.

Australia has stringent rules about who should be allowed to enter the country, with tennis players needing to be either vaccinated or hold a medical exemption in order to play the grand slam tournament.

Serbian superstar Djokovic wrote on Instagram: "I’ve spent fantastic quality time with my loved ones over the break and today I'm heading Down Under with an exemption permission. Let's go 2022!!"

World number four Stefanos Tsitsipas is optimistic he will be fit for this month's Australian Open after coming through his first complete singles match since undergoing surgery on his right elbow last November.

Following a gruelling three-set defeat to Diego Schwartzman at the ATP Cup in Sydney on Monday, Tsitsipas was upbeat about his prospects of performing in Melbourne.

"It gets better and better every single day", Tsitsipas said of his injury. "We have plenty of time before the Australian Open begins, and I think if I take the right precautions and follow what my doctor says, then I can see myself performing at 100 per cent.

The Greek went on to reveal that medics had harboured serious doubts over his participation at the first Grand Slam of 2022, after he had been forced to withdraw from November's ATP Finals in Turin.

"Going into that surgery, even the doctor was unsure if it was a good idea to perform and play at the Australian Open.

"My recovery was much better than he expected, in comparison with other players that he has treated in the past, so he was surprised. He came to Dubai, and he was surprised to see me hitting close to 100 per cent.

The 2021 French Open finalist also claimed to have enjoyed his contest with Schwartzman, despite the defeat.

"It was good to see myself perform at such a level. I didn't expect it," he said. "It worked out better than I thought. I was able to hit balls that I was scared to hit two weeks ago, so I’m heading towards the right direction."

Tsitsipas, who has won seven ATP Tour events to date, is due to be in action once more in Sydney this week against Georgian, Nikoloz Basilashvili.

Laslo Djere and Soonwoo Kwon began 2022 by cruising through the opening round of the ATP Adelaide International, both earning straight set wins to reach the round of 16. 

Number seven seed Djere beat Spaniard Roberto Carballes Baena 7-5 7-6 (7-1) on the hard surface, while eighth seed Kwon comfortably saw off Japan's Yoshihito Nishioka 6-1 6-2.

Elsewhere, Thiago Monteiro earned an entertaining 6-2 3-6 7-6 (7-2) win over Daniel Altmaier, and the Brazilian will now face number three seed Marin Cilic in the round of 16 after the 2014 US Open champion was given a first round bye.

The other encounter on Monday saw Steve Johnson come through in three sets against wildcard Aleksandar Vukic, 6-4 2-6 6-4. The American will go up against second seed Karen Kachanov in the last 16.

Two-time Grand Slam semi-finalist Gael Monfils is the top seed for the ATP 250 tournament, with Cilic, Khachanov and Frances Tiafoe among the other big names who will enter the competition in the next round.

Diego Schwartzman sealed a 2-0 win for Argentina over Greece in Group D of the ATP Cup after edging a close contest with world number four Stefanos Tsitsipas.

Schwartzman claimed just the third victory of his career over a top-five opponent, winning 6-7 (5-7) 6-3 6-3 in Sydney.

The world number 13 fought back from a break down in the second set before taking his career head-to-head with Tsitsipas to 2-1 after battling through two hours and 42 minutes on Ken Rosewall Arena.

"I was just trying to think that it was his first match for two months after his elbow [injury], so I was thinking just to try and be in the match," Schwartzman said in his on-court interview.

"I had the chance and I think I was ready. I am very happy because playing against Stefanos and being a set and a break down is not easy, but I found a way."

Argentina, who earlier saw Federico Delbonis defeat Michail Pervolarakis in straight sets, will now face Poland on Wednesday to decide who progresses to the semi-finals.

Poland were comfortable 3-0 winners in their match-up with Georgia, Kamil Majchrzak beating Aleksandre Bakshi for the loss of just two games before Hubert Hurkacz defeated Aleksandre Metreveli 6-7 (5-7) 6-3 6-1.

Pablo Carreno Busta beat Viktor Durasovic 6-3 6-3 to put Spain ahead against Norway, and their win was assured when Roberto Bautista Agut claimed an impressive 6-4 7-6 (7-4) victory over Casper Ruud. Alejandro Davidovich Fokina and Pedro Martinez followed up with a straight-sets doubles win.

"Casper is playing unbelievable tennis, [he did] an unbelievable performance last year, and today I played very good," Bautista Agut said. "I returned very well, I made very few unforced errors and I played aggressively. I try to play matches like this and that is why I am practising hard and I am trying to show this level."

Spain are top of Group A ahead of Serbia, whose match with Chile will go down to a doubles decider.

Daniil Medvedev suffered a shock loss in his first match of the year as the US Open champion was beaten by Ugo Humbert at the ATP Cup.

World number two Medvedev led by a set and 3-0 but stumbled from there and went down 6-7 (5-7) 7-5 7-6 (7-2) at the team event in Sydney.

He put that defeat behind him and paired up with Roman Safiullin in doubles to clinch a 2-1 victory for Russia over France in the round-robin Group B tie.

Medvedev and Safiullin were 6-4 6-4 winners over Fabrice Martin and Edouard Roger-Vasselin in the tie decider, with world number 167 Safiullin having earlier scored an impressive 2-6 7-5 6-3 singles victory over Arthur Rinderknech.

Humbert's remarkable comeback victory over Medvedev was the standout result of the contest, however, with the 23-year-old French left-hander saying afterwards: "It was a very tough match. I am very happy."

Metz-born Humbert added, quoted on the ATP website: "I had some opportunities in the first set and I just tried to stay relaxed and focused on what I had to do. It was a great match."

Australia had an eye-catching win in the same group, landing a 2-1 success over Italy, helped by Alex de Minaur beating Wimbledon runner-up Matteo Berrettini.

De Minaur scored a 6-3 7-6 (7-4) win to level the tie after Jannik Sinner swept past Max Purcell 6-1 6-3, with Berrettini and Simone Bolelli then beaten 6-3 7-5 in a late-night doubles tussle by John Peers and Luke Saville.

In Group C, Great Britain scored a 2-1 win over Germany, with Dan Evans and Jamie Murray teaming up in doubles to beat Alexander Zverev and Kevin Krawietz 6-3 6-4 to take the tie.

Zverev had earlier been too good for Cameron Norrie, posting a 7-6 (7-2) 6-1 win, after Evans sped to a 6-1 6-2 victory over Jan-Lennard Struff.

In their next tie, Germany will do battle with a United States side who were impressive 3-0 winners against Canada on Sunday. John Isner and Taylor Fritz scored singles victories over Brayden Schnur and Felix Auger-Aliassime before pairing up to beat Auger-Aliassime and Denis Shapovalov in doubles.

Australian Open tournament director Craig Tiley says it should become clear in "the coming days" if Novak Djokovic will defend his title at Melbourne Park this month.

Djokovic withdrew from the ATP Cup in Sydney last week and has not yet arrived in Melbourne for the first grand slam of the year.

Players must be vaccinated or have a medical exemption in order to play in the opening major of 2022 and Djokovic has refused to disclose whether he has been jabbed.

Tiley is unsure whether the world number one will go in search of a record 21st grand slam title at the Australian Open, which starts on January 17.

"We've still got a few charter flights coming in until the end of this week and then all the players will be here," he told the Nine Network.

"As far as the status relates to Novak, I think we'll have a much clearer picture in the coming days otherwise it's getting pretty late to show up and play the Australian Open."

He added: "There's quite a bit to play out and I think it will play out in the coming days."

Djokovic has won the Australian Open men's singles title a record nine times and beat Daniil Medvedev in the 2021 final. 

Stefanos Tsitsipas withdrew from his ATP Cup match against Hubert Hurkacz on Saturday but eased injury fears after playing in the doubles.

The Greek star, ranked fourth in the world, is recovering from elbow surgery but suffered a flare-up of the problem in Sydney and pulled out of the Group D singles tie as a precaution.

With the Australian Open coming up later this month, the two-time Melbourne Park semi-finalist appeared comfortable as he paired up with Michail Pervolarakis for a 6-4 5-7 10-8 win.

"The recovery from my elbow surgery in November is on track for Melbourne and today was a precautionary step to make sure I make Melbourne," he said.

"We will see day by day, match by match until then."

Aristotelis Thanos stepped in for Greece and lost 6-1 6-2 as Hurkacz helped Poland into a 2-0 lead after Kamil Majchrzak had beaten Pervolarakis 6-1 6-4, making the doubles clash a dead rubber.

Spain, runners-up in 2020, showed no mercy on Chile despite the absence of Rafael Nadal as they stormed to a 3-0 win in Group A.

Roberto Bautista Agut downed Cristian Garin 6-0 6-3, while Pablo Carreno Busta defeated Alejandro Tabilo 6-4 7-6 (7-4). Doubles pairing Alejandro Davidovich Fokina and Pedro Martinez battled to a 7-6 (7-3) 4-6 10-7 victory over Tabilo and Tomas Barrios.

Argentina also enjoyed a 3-0 triumph in Group D, with Georgia coming up blank against a team led by Diego Schwartzman.

Serbia, without Novak Djokovic, earned a decisive doubles success to seal a 2-1 win over Norway, with Nikola Cacic and Filip Krajinovic downing Casper Ruud and Viktor Durasovic.

World number one Novak Djokovic has withdrawn from the ATP Cup in Sydney amid ongoing uncertainty over his title defence at next month's Australian Open.

Djokovic has not yet confirmed his place at January's Grand Slam due to the COVID-19 mandate in Victoria.

The 34-year-old's father, Srdjan, has previously said that the nine-time Australian Open champion is unlikely to feature in Melbourne unless vaccination rules are relaxed.

World number 33 Dusan Lajovic will now lead the Serbia team at the ATP Cup.

Meanwhile, Austria have been replaced by France at the event following the withdrawals of Dominic Thiem and Dennis Novak. The French will be led by world number 35 Ugo Humbert, alongside Arthur Rinderknech, Edouard Roger-Vasselin and Fabrice Martin.

Russia's Andrey Rublev, Aslan Karatsev and Evgeny Donskoy have withdrawn, with Evgeny Karlovskiy joining the team, while Team USA's Austin Krajicek has also pulled out.

The ATP Cup will begin on New Year's Day at both Ken Rosewall Arena and Qudos Bank Arena, Sydney Olympic Park.

Dominic Thiem has withdrawn from next month's Australian Open.

Thiem has not played on the ATP Tour since suffering a wrist injury at the Mallorca Championships in June.

The 2020 US Open champion was due to feature in the Mubadala World Tennis Championship in Abu Dhabi this month, but withdrew after suffering a setback.

Thiem on Tuesday revealed his wrist is in "optimal condition", but the Austrian will miss the first grand slam of the year at Melbourne Park and will instead make his comeback at the Cordoba Open next month.

The Austrian tweeted: "As you all know, I came back home to Austria to recover after hard practice sessions I had in Dubai and the slight setback in my preparation. I am now feeling well again, my wrist is in optimal condition and I am practicing normally with a very good intensity.

"After my short holidays, my team and I have assessed all matters and we have decided to make some changes to my initial tournament schedule.

"I will start the season in South America at the Cordoba Open in Argentina, end of January, and therefore I will not play this year at the Australian Open in Melbourne, a city that I love and where I have great memories of unforgettable matches in front of amazing crowds. I will miss the Australian fans but I will be back in 2023.

"We believe this is the right decision in order to have a good return to competition. For the moment I will remain in Austria for a few more days and then head to practice outdoors and get ready for my first event of the season."

The 28-year-old was a runner-up in the 2020 Australian Open before going on to claim his first major title at Flushing Meadows.

Alexander Zverev believes he will form a big three with Novak Djokovic and Daniil Medvedev in 2022 but hopes he will not get the chance to become world number one at the Australian Open.

The German is knocking on the door near the top of the rankings after a fine year that saw him win six titles, including the season-ending ATP Finals in Turin and an Olympic gold medal in Tokyo.

Zverev, currently ranked third, could go top of the rankings if he wins the Australian Open, which starts next month, but that is only possible if current world number one Djokovic does not play.

And Zverev is hopeful the Serbian will take part despite continued uncertainty over his participation in the tournament amid intense debate over his COVID-19 vaccine stance.

Djokovic, a nine-time Australian Open winner, is yet to disclose his vaccination status.

Tournament chief Craig Tiley said this week he is still hoping to see the tour's top player participate if he meets the required conditions, which are either being vaccinated or having a medical exemption.

"The situation with Novak and Australia is still a big question mark," Zverev said in a podcast appearance with Eurosport Germany. 

"Of course, I hope that he will be allowed to play, that is very clear.

"There are thousands of mathematical calculations, if he doesn't play Australia and I win the Australian Open, then I'm number one in the world and so on and so forth.

"At the end of the day, now is not the time to think about [being world number one]. Now is the time to prepare as best as you can so you're physically able to play for it."

As well as his silverware, Zverev made the last four of the French Open and US Open, and the 24-year-old believes his experience has begun to come to the fore.

Zverev had a 59-15 record this season and recorded at least one victory against every other player inside the top 10 of the ATP year-end rankings.

"I've become much calmer and I'm also getting older," he added.

"I'm not 18 or 19 anymore. I understand maybe a bit more things about life and understand that you just have to keep calm in important situations. That has had its effect on me this year.

"I think next year could be very similar to the last six months from this year.

"Before, there used to be always talk about Rafael Nadal, Roger Federer and Novak Djokovic – now the big titles were the Olympics, US Open, Turin and Wimbledon, and they were all won by Medvedev, Djokovic and me. 

"I don't expect it to be any different next year."

Alexander Zverev believes he will form a big three with Novak Djokovic and Daniil Medvedev in 2022 but hopes he will not get the chance to become world number one at the Australian Open.

The German is knocking on the door near the top of the rankings after a fine year that saw him win six titles, including the season-ending ATP Finals in Turin and an Olympic gold medal in Tokyo.

Zverev, currently ranked third, could go top of the rankings if he wins the Australian Open, which starts next month, but that is only possible if current world number one Djokovic does not play.

And Zverev is hopeful the Serbian will take part despite continued uncertainty over his participation in the tournament amid intense debate over his COVID-19 vaccine stance.

Djokovic, a nine-time Australian Open winner, is yet to disclose his vaccination status.

Tournament chief Craig Tiley said this week he is still hoping to see the tour's top player participate if he meets the required conditions, which are either being vaccinated or having a medical exemption.

"The situation with Novak and Australia is still a big question mark," Zverev said in a podcast appearance with Eurosport Germany. 

"Of course, I hope that he will be allowed to play, that is very clear.

"There are thousands of mathematical calculations, if he doesn't play Australia and I win the Australian Open, then I'm number one in the world and so on and so forth.

"At the end of the day, now is not the time to think about [being world number one]. Now is the time to prepare as best as you can so you're physically able to play for it."

As well as his silverware, Zverev made the last four of the French Open and US Open, and the 24-year-old believes his experience has begun to come to the fore.

Zverev had a 59-15 record this season and recorded at least one victory against every other player inside the top 10 of the ATP year-end rankings.

"I've become much calmer and I'm also getting older," he added.

"I'm not 18 or 19 anymore. I understand maybe a bit more things about life and understand that you just have to keep calm in important situations. That has had its effect on me this year.

"I think next year could be very similar to the last six months from this year.

"Before, there used to be always talk about Rafael Nadal, Roger Federer and Novak Djokovic – now the big titles were the Olympics, US Open, Turin and Wimbledon, and they were all won by Medvedev, Djokovic and me. 

"I don't expect it to be any different next year."