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."

Andy Murray will compete at the Australian Open for the first time in three years after being awarded a main-draw wildcard.

Murray has finished as a runner-up five times at Melbourne Park – most recently in 2016 when he was beaten by Novak Djokovic 6-1 7-5 7-6 (7-3).

The Scot has since struggled with a hip injury that had him on the verge of retirement, while he dropped to 134th in the world rankings.

However, the former world number one was in action at the Mubadala World Tennis Championship in Abu Dhabi last week, where he defeated Rafael Nadal before eventually falling to Andrey Rublev in the final of the exhibition event.

Murray was due to feature at the Australian Open in 2020 before a positive coronavirus test stopped him from playing, but the 34-year-old is thankful for the chance to compete in Melbourne again.

"I'm really excited to be back playing at the Australian Open and grateful to Craig [Tiley] and the team for the opportunity," Murray said on his wildcard, as quoted by the tournament's website.

"I've had some great times in Australia playing in front of the amazing crowds and I can't wait to step back out on court at Melbourne Park."

Tournament director and Tennis Australia chief executive Craig Tiley added: "Andy is renowned for his fighting spirit, passion and love of the game, and I'm delighted to welcome him back to Melbourne in January."

American Stefan Kozlov and Frenchman Lucas Pouille join Murray as the men's singles wildcards so far, with the other four spots likely to go to Australians and another to an Asia-Pacific player.

The Australian Open gets underway on January 17 with the final set to take place 13 days later.

Australian Open chief Craig Tiley wants Novak Djokovic to participate in Melbourne but will not ask the world number one to disclose any medical reason he has for being unvaccinated against COVID-19.

The first grand slam of 2022 begins on January 17, but it is unclear if reigning champion Djokovic will be competing.

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

Following guidance from the Victoria state government, all players, staff and spectators at Melbourne Park must have been fully vaccinated against coronavirus or hold a medical exemption.

Djokovic has been named on the list for the draw and is also due to represent Serbia at the ATP Cup in Sydney, which runs from January 1 to 9.

"If Novak shows up, he'll be vaccinated or have a medical exemption," Australian Open chief executive Tiley told the Australian Associated Press.

"If any player, fan [or] workforce is on site here, you're either vaccinated or you have a medical exemption that's approved and you're on the Australian Immunisation Register.

"That provides us with safety and an extra level of comfort on site.

"We want to have the best players here; I'd love to have Novak here. If he meets those conditions then great, if not, it's disappointing."

Tiley added he does not expect Djokovic to reveal any medical reason for which he may not have received the vaccine, should he receive a medical exemption to feature in the tournament.

"Medically, he doesn't talk to anyone about it. I'm not going to ask Novak that, it's none of my business," Tiley continued.

"[It's] his choice on his medical condition, it's his choice to keep personal and private like all of us would do with any condition we may or may not have. We are not going to force him or ask him to disclose that.

"[If he is here] I will know that he fulfils one of those conditions."

Rafael Nadal is set to play in Melbourne, though that is in doubt after the Spaniard tested positive for COVID-19 this week, following his appearance at the Mubadala World Tennis Championship in Dubai.

Tiley, however, believes Nadal will have recovered in time.

"I'm confident Rafa will be here," said Tiley. "Players that are testing positive now will complete a period of time until they are no longer infectious and they will be fine.

"If you are going to test positive and you want to play the Australian Open, your timing would be now."

Tokyo Olympics gold medalist Belinda Bencic has tested positive for COVID-19 ahead of next month's Australian Open and is experiencing "severe" symptoms.

World number 23 Bencic returned a positive test, along with Ons Jabeur, after competing at the Mubadala World Tennis Championship in Abu Dhabi.

The pair are the third and fourth players to have tested positive after travelling to the Abu Dhabi event, following 2021 US Open winner Emma Raducanu and 20-time major winner Rafael Nadal.

Bencic wrote on Twitter: "Unfortunately and even though I am fully vaccinated, I recently tested positive for Covid-19.

"I am currently isolating and taking all precautionary [measures] to get through this as best as possible as I am experiencing quite severe symptoms (fever, aches, chills)."

The Mubadala World Tennis Championship typically serves as a warm-up event prior to the Australian Open which is due to begin on January 17 in Melbourne.

World number 10 Jabeur, who defeated Bencic in Abu Dhabi, is experiencing "strong symptoms" and isolating in her native Tunisia.

Rafael Nadal has tested positive for coronavirus on his return to Spain, leaving his participation at the Australian Open in doubt.

The 20-time major champion played at the Mubadala Tennis Championship in Abu Dhabi last weekend and declared his mission a success despite consecutive defeats on his return from a foot injury.

Indeed, Nadal had only competed in two matches since losing to Novak Djokovic in the French Open semi-finals in June before testing his long-term foot problem against Andy Murray and most recently Denis Shapovalov.

However, the 35-year-old's plans to feature in the Melbourne ATP 250 ahead of the Australian Open in early January have suffered a setback after he tested positive for COVID-19 upon landing in his home country on Monday.

Nadal revealed the news on Twitter as he posted: "I wanted to announce that on my return home after playing the Abu Dhabi tournament, I have tested positive for COVID in the PCR test that was performed on me when I arrived in Spain.

"Both in Kuwait and Abu Dhabi we passed controls every two days and all were negative, the last being on Friday and having the results on Saturday.

"I am having some unpleasant moments but I hope that I will improve little by little. I am now homebound and have reported the result to those who have been in contact with me.

"As a consequence of the situation, I have to have total flexibility with my calendar and I will analyse my options. I will keep you informed of any decisions about my future tournaments!"

Nadal was eyeing the Australian Open, which starts on January 17, as his first major comeback, though he earlier admitted his entry was not guaranteed as he evaluated his foot injury and physical fitness.

"I cannot guarantee Australia one hundred per cent, because I need to go home and see how the body responds after these days," Nadal told reporters on Saturday. 

"I have time to make a decision. At this point in my career, I need to go day by day, study each movement well.

"I have been able to show a competitive level against good players even without being in perfect condition. There are things to improve but looking at things with perspective it has been a positive tournament [in Abu Dhabi].

"The main objective is to be healthy enough to do the things that I need to do and aspire to the objectives that I have always had. The illusion and passion continue to exist."

The ATP Tour event in Melbourne, which would be Nadal's first such tournament since August, is due to start on January 3.

Dominic Thiem will skip the Australian Open if he is not happy with his fitness at the end of December, the former US Open champion said on Sunday.

The 28-year-old has not played on the ATP Tour since suffering a wrist injury at the grass-court Mallorca Championships in June.

Thiem missed Wimbledon and could not defend his grand slam title at Flushing Meadows, with injury fears lingering ahead of the new season.

Despite not requiring surgery on the damaged wrist, Thiem has been unable to play competitively and experienced a fresh setback this month when he pulled out of the Mubadala World Tennis Championship, an exhibition event in Abu Dhabi.

In announcing that decision on December 14, Thiem said he was "not yet ready to compete at the highest level", and there was little to inspire confidence when he issued an update confirming he would not travel to play in two events ahead of the Australian Open.

Although Thiem still wants to play at Melbourne Park, where the slam begins on January 17, his prospects are hinging on him feeling significantly more optimistic about his game and fitness in a matter of days.

Thiem wrote: "After speaking to my team, we have decided to return to Austria, instead of flying directly to Australia.

"Unfortunately, I caught a cold [and tested negative for COVID-19] while in Dubai and was unable to practise last week. I will therefore not be in the physical condition required to be able to play the ATP Cup and Sydney ATP 250.

"After not competing for the last six months I can't take the risk of coming back too soon and picking up a further injury.

"Overall, the time I spent in Dubai was great as I've increased the intensity and level of practise and my wrist is almost at 100 per cent.

"My aim is still to play the Australian Open but we will make a final decision about my participation by the end of December."

Rafael Nadal declared his Abu Dhabi mission a success despite suffering a second consecutive defeat at the Mubadala Tennis Championship on Saturday.

After a hard-fought battle with Andy Murray on Friday served up a reminder of many a classic match between the pair, it was Denis Shapovalov who beat Nadal in his second comeback clash.

Since losing to Novak Djokovic in the French Open semi-finals in June, Nadal had played only two matches due to a worrying foot injury.

That has been a long-term problem and the 35-year-old Spaniard chose this week's event to test how it would stand up to match conditions.

Canadian Shapovalov beat his fellow left-hander 6-7 (4-7) 6-3 10-6, but Nadal has done enough in his two matches, and in a practice session with Andrey Rublev, to be persuaded his prospects for 2022 are looking up, with the Australian Open just a month away.

The 20-time grand slam champion said: "Maybe it was too tough to start after a long time."

But he was laughing as he said that, and added: "The goal is achieved: to be back on court. I've played two matches and played more or less four hours on court.

"I enjoyed it. Congrats to Denis today. I wish you all the very best for the next season, and I'm going to try to keep going with my road."

Nadal said he would return to the tournament in future years, as long as he remains fit and still on tour.

"If I'm still playing tennis, I am always super happy to be here playing," he said. "Hopefully I can keep coming during the next couple of years."

Shapovalov, 22, is one of the ATP Tour's most talented youngsters, striving to make a telling impact while the likes of Nadal, Novak Djokovic and Murray reach the twilight years of their careers.

He said of Saturday's win over Nadal: "Any time I get to go on court against a guy like Rafa is an honour for me.

"It's great to just see you back on the court and see you healthy. Hopefully you can grab a great season and keep going."

Rafael Nadal said it felt "special" to be back on court as the 20-time grand slam champion began his latest comeback with defeat to old foe Andy Murray in Abu Dhabi.

The Spaniard was beaten 6-3 7-5 by Murray at the Mubadala World Tennis Championship, an exhibition event that for the 35-year-old marks an important step towards a full ATP tour return.

Nadal is coming off a year disrupted by the foot injury that caused him to miss Wimbledon, the Olympics and the US Open, playing just one event after June.

With the Australian Open a month away, there is plenty of work for these two still to do, but this was a feast for the eyes as the multiple grand slam champions jostled hard for supremacy.

Murray is down at 134th in the ATP rankings and continues to battle his own body after hip and groin problems. However, eye-catching wins late in the season against the likes of Carlos Alcaraz, Hubert Hurkacz, Jannik Sinner and Frances Tiafoe have suggested there might be good times ahead for him in the new year.

Here the Scot broke Nadal's serve to 15 in the sixth game of the first set to seize the initiative. Nadal appeared to be finding a familiar rhythm in the second set, hitting some tremendous clean winners, and at 0-30 down at 4-4 he serve-volleyed twice in succession to get out of trouble.

A contentious line call gave Murray two break points at 5-5, and although Nadal saved one, he fired long at the end of a super rally on the next point. Murray closed out the contest on his second match point, with Nadal flinging a full-throttle backhand long, 

"It's been special to be back in competition," Nadal said in an on-court interview. "At the same time, it's been a while since we played against each other. I'm super happy to see Andy playing at this great level after all the things he went through.

"For me, as a comeback it was not a bad match for me. It's been a long time since I was out on court in a professional match so I've got positive feelings."

These wily old rivals had met 24 times previously at competitive tour level, all of those encounters coming between 2007 and 2016 with Nadal leading 17-7 in the head-to-head.

Nadal won the ATP's comeback player of the year award way back in 2013, and he finds himself looking to prove himself again in 2022, locked together on 20 slams with Novak Djokovic and Roger Federer.

Murray, who has won three slams but also been a runner-up eight times in the majors, said: "It's great to be back on the court, able to play at a high level again after a very long time. Me and Rafa have played so many tough matches, but we've not played for five or six years.

"That shows both of us have gone through lots of injury troubles and issues, and it's great to just have the opportunity to be on the court with him again.

"Certainly when I was younger I wasn't appreciating it as much as I do now. It's great to be back on the court, I'm so happy that Rafa's back, and I look forward to the next few years."

Murray will play Andrey Rublev for the title on Saturday, while Nadal features again too, taking on Denis Shapovalov in a third-place match.

Dominic Thiem's comeback has been further delayed as the 2020 US Open champion does not feel ready to return at this week's Mubadala World Tennis Championship.

Austrian star Thiem has been out of action since suffering a wrist injury at the Mallorca Championships in June.

The 28-year-old missed Wimbledon and was unable to defend his title at Flushing Meadows, but he appeared to be on course to make his comeback before the end of 2021 after revealing in October he does not require surgery on his wrist.

However, the world number 15 is now facing a battle to be back to full fitness for January's Australian Open after withdrawing from an exhibition event in Abu Dhabi.

"I was looking forward to making my return to competition at Abu Dhabi but I feel that I am not yet ready to compete at the highest level," the 17-time ATP Tour champion posted via Twitter on Tuesday.

"It's disappointing to not take part this year but I need to continue my preparation for the upcoming season."

Thiem follows Casper Ruud in pulling out of the tournament, which begins on Thursday, while Emma Raducanu is out of the women's singles after testing positive for coronavirus.

Dan Evans and Taylor Fritz have taken the places of former world number three Thiem and Ruud, joining Andrey Rublev, Denis Shapovalov, Andy Murray and defending champion Rafael Nadal in the draw.