Tokyo Olympics organisers have confirmed the first case of COVID-19 at the athletes' village, raising further concerns about the Games going ahead.

Thousands of athletes and media personnel are arriving in the Japanese capital ahead of the global competition beginning on July 23.

There has already been a total of 44 coronavirus cases linked to the Olympics, including one overseas visitor who is involved in organising the Games.

The person in question, whose nationality has not been disclosed for privacy reasons, is now quarantining for 14 days in a hotel room.

Tokyo 2020 CEO Toshiro Muto confirmed the news at a news conference on Saturday and added: "That positive cases arise is something we must assume is possible."

Around 11,000 athletes from 205 national Olympic committees are expected to stay at the Olympic Village over the next three weeks.

Speaking earlier this week, International Olympic Committee president Thomas Bach vowed Tokyo would host a "safe and secure" Olympics.

IOC official Joan Coates also insisted it was down to organisers to ensure the Olympic Village "is the safest place in Tokyo".

Following news of Friday's positive case in the camp, however, Games chief Seiko Hashimoto says it is understandable that some athletes may be concerned.

"Athletes who are coming to Japan are probably very worried. I understand that," Hashimoto said.

"That is the reason why we need to make full disclosure.

"We are doing everything to prevent any COVID-19 outbreaks. If we end up with an outbreak we will make sure we have a plan in place to respond."

The 2020 Games, delayed by a year, will be held mostly without spectators after a state of emergency was called in Tokyo amid rising coronavirus cases.

Another 1,271 new COVID-19 cases were reported on Friday, compared to 822 on the same day last week.

Alex de Minaur is "shattered" to be missing the Tokyo Olympics after he tested positive for COVID-19.

De Minaur was the headline name of Australia's Olympics men's tennis team, alongside Nick Kyrgios.

However, Kyrgios pulled out last week due to a concern over the decision to ban fans from attending events due to a spike in coronavirus cases in Japan.

Now world number 17 De Minaur has joined a list of absentees which already includes Roger Federer and Rafael Nadal, while the woman's tournament will be without Serena Williams and former medallists Victoria Azarenka and Angelique Kerber, who withdrew on Friday.

"We have been advised that Alex de Minaur has had a positive test, as a consequence, Alex, sadly will be unable to join the Australian team," Australia's chef de mission Ian Chesterman said.

"We are very disappointed for Alex and he is shattered at not being able to come. It has been his dream to represent Australia at the Olympic Games since he was a child, but he sent his best wishes for the team."

De Minaur undertook both the mandatory 96-hour and 72-hour PCR tests before departure. However, Australia are confident his positive result will have no impact on the rest of their team.

The 22-year-old was set to take part in his first Games, representing Australia in the singles and doubles.

"No other tennis players have had physical contact with Alex since he left Wimbledon on 5 July, where he tested negative," Chesterman added.

"All other Australian players have tested negative since. We look forward to welcoming those athletes into our team.

"We need to protect this bubble and Alex has been caught up in that system. While we will miss Alex, he understands the reasons why he cannot be with us."

Novak Djokovic has confirmed he will enter the Olympic Games in Tokyo, with the world number one just two titles away from a first men's Golden Slam.

Rivals Rafael Nadal and Roger Federer, citing respective scheduling and injury issues, have each withdrawn from Tokyo 2020.

But Djokovic confirmed on Thursday he will travel to Japan in pursuit of a groundbreaking achievement.

Only women's tour legend Steffi Graf has previously won all four majors and the Olympics in the same year, doing so in 1988.

Doubles superstars Bob and Mike Bryan held all five titles at once but collected them across 2012 and 2013, while Andre Agassi and Nadal are the only two men's singles players to achieve the feat across an entire career.

Djokovic has already triumphed at the Australian Open, French Open and Wimbledon in 2021, leaving Tokyo and the US Open still to conquer.

The 20-time grand slam champion – a record he tied at the All England Club on Sunday – has entered the Games three times previously but earned only a single bronze medal. Andy Murray is the two-time defending champion.

At Flushing Meadows, Djokovic is a three-time winner.

The 34-year-old confirmed his Olympics plans in a social media post as he sent a message to a young Japanese fan celebrating his sixth birthday.

"Cannot disappoint my little friend Koujirou," Djokovic wrote. "I booked my flight for Tokyo and will proudly be joining #TeamSerbia for the Olympics."

He had said following his Wimbledon win last week: "My plan was always to go to Olympic Games, but right now I'm a little bit divided."

Djokovic added limitations on his travelling party and potentially being unable to watch fellow athletes had reduced the likelihood of an appearance to "50-50".

But he will now feature, even if former Wimbledon champion Pat Cash believes the calendar Grand Slam – winning the four majors but not the Olympics – has to be the Serbian's priority.

Cash told Stats Perform: "It's the Olympics, okay – maybe he wants to do that, but certainly his goal is now to try and win all four grand slams in the calendar year.

"He has done four in a row, but he hasn't done them in the same year, which is very, very tough to do.

"There is a reason why I think one person has done it in [men's] professional tennis – Rod Laver and it was in 1969, so it's not easy to do.

"But I really do think it's in his sights and that has got to be his priority.

"It's absolutely the absolute peak of our sport to win all four grand slams in one year."

Angelique Kerber will not be going for gold for Germany at the Tokyo Olympics, with the three-time grand slam winner withdrawing on Thursday.

One week on from losing to Ash Barty in the Wimbledon semi-finals, Kerber said it was "disappointing" to pull out of the Games.

The former Australian Open, Wimbledon and US Open champion said in a statement: "The thought of participating at the Olympics has been a constant motivation for me over the past months to push further and keep believing in my goals.

"Representing Germany in London 2012 and Rio 2016 as part of the German team has always been one of my favourite memories of my career so far.

"This makes it even more disappointing for me to accept the fact that my body needs rest after the intense few weeks that lie behind me and that I have to recover first before returning to competition later this summer!

"Thank you for your support, as this has been a very difficult decision for me. Good luck to all my fellow German athletes in Tokyo #TeamDeutschland, I will miss you."

Kerber reached the Olympic final in Rio in 2016 but suffered a shock defeat in the title match to Monica Puig of Puerto Rico, having to settle for the silver medal.

Her absence this year means the field is further depleted, with Serena Williams, Bianca Andreescu, Simona Halep and Sofia Kenin among the high-profile WTA Tour stars who will be absent in Japan. Puig will also miss out after undergoing shoulder surgery.

The men's line-up has been similarly hit, with Roger Federer, Rafael Nadal and Dominic Thiem choosing not to play.

Roger Federer's body has been saying no for the past two years, but Pat Cash is hopeful the 39-year-old will return for another run on the ATP Tour.

After suffering a setback to his longstanding knee injury during Wimbledon, the 20-time grand slam champion has this week withdrawn from the Tokyo Olympics.

Despite being without much match practice – playing just four tournaments before Wimbledon after coming back from two knee surgeries - Federer was able to make the quarter-finals at All England Club.

However, he suffered a demoralising loss to Hubert Hurkacz in straight sets in the last eight that promoted a fresh round of speculation over his future in the game.

Cash, who won Wimbledon in 1987, hopes Federer will be back despite his recent injury woe.

He told Stats Perform: "First of all, let's hope that Roger Federer will keep going. 

"I think he can, I think he just needs more matches and probably needs to make sure that he's able to last. 

"But your body starts saying no at some stage and it's been saying that for a couple of years now for him." 

Wimbledon winner Novak Djokovic is now level with Rafael Nadal and Federer on 20 slams.

Cash believes judging the Swiss star purely on grand slam titles is not a fair measure of his brilliance, pointing instead to his astonishing record totals of 58 major quarter-final berths and 46 semis.

"He has been the most consistent player that I think we've ever seen," Cash said. "He may not end up with as many grand slams but his consistency is just outrageous.

"All the other players have lost early in grand slams, the Djokovics, the [Andy] Murrays, then the Nadals had lost early in grand slams, Roger just doesn't do it.

"Of all the titles that he's won, I think for me, his most impressive record is how many semi-finals or quarter-finals in grand slams in a row that he got to. It was something ridiculous for 10 or 11 years.

"He never failed at any grand slams and that is just absolutely mind blowing."

However long he tries to play on, Cash insists nothing can sour the memories of an extraordinary career from Federer.

Cash added: "Obviously, he raised the bar as far as the standard of tennis has gone. 

"The other players really had to catch up. Novak admitted it, he said, 'Without Roger there, leading the way, I wouldn't have been as good a player as I could have been'. 

"That's the gold standard of Roger Federer over his career and I'm not sure anybody will be as consistent as him in tennis history. 

"He's just phenomenal the way he plays, and we all of course enjoy the style, his movement. And he's a class act off the court as well."

Federer's status for the US Open, which begins on August 30, is unclear, with Djokovic looking to take the outright lead for major titles and achieve a historic calendar year Grand Slam.

American Trayvon Bromell reinforced his favouritism for gold at the Tokyo Olympics after flying to victory in the men's 100m sprint at Gateshead on Tuesday.

Bromell won the final Diamond League race prior to the Olympics in 9.98 seconds from British pair CJ Ujah (10.10) and Zharnel Hughes (10.13) in second and third respectively.

The victory at Gateshead was 26-year-old Bromell's first-ever Diamond League triumph, following years plagued by injuries.

"I’ll take the win,” Bromell said. “I’m happy to cross the line with no injuries.

"I’m just trying to tune up for Tokyo, stay mentally relaxed and continue to fight."

Bromell started strong and finished well ahead of the field, despite Ujah's surge.

“I know I can do better than that. I want the gold," Ujah said. "This is a different CJ and I am really excited.

"It’s now about getting out to Japan, acclimatising and preparing for the race.”

Switzerland's Ajla Del Ponte won the women's 100m in 11.19 seconds, ahead of Canadian pair Khamica Bingham and Crystal Emmanuel.

Jamaican Elaine Thompson-Herah claimed her career 23rd Diamond League win in the women's 200m in 22.43 seconds.

“I am very pleased. I am going to train, reset and stay focused,” the Olympic champion said.

Britain's Jodie Williams ran second in the 200m before competing in the 400m less than an hour later and finishing second with a personal best 50.94 behind Stephenie McPherson.

Ronald Levy won the men's 110m hurdles in 13.22, while Cindy Sember won the women's equivalent in 12.69.

Roger Federer has withdrawn from the Tokyo Olympics because of a setback to his knee suffered during the grass-court season.

Olympic gold in singles is one of the few honours missing from Federer's glittering resume, the 20-time grand slam champion having won silver in 2012, losing the gold medal match to Andy Murray less than a month after beating the Briton in the Wimbledon final.

While Murray will be in Tokyo to attempt to defend his title again having successfully retained it in 2016, Federer – a doubles gold medallist in 2008 – has elected not to make the trip to Japan.

"During the grass-court season, I unfortunately suffered a setback with my knee, and have accepted that I must withdraw from the Tokyo Olympic Games," Federer wrote in a statement on Twitter.

"I am greatly disappointed, as it has been an honour and highlight of my career each time I have represented Switzerland.

"I have already begun rehabilitation in the hopes of returning to the tour later this summer. I wish the entire Swiss team best of luck and I will be rooting hard from afar. As always, Hopp Schwiz!"

Federer missed most of the 2020 season due to persistent right knee problems that led him to undergo two surgeries.

The length of his recovery forced Federer to miss this year's Australian Open but he made his return to the tour in time for the French Open, reaching the fourth round before withdrawing to focus on the grass-court season.

Yet he was stunned by Felix Auger-Aliassime in the second round in Halle and was often unconvincing in progressing to the quarter-finals at Wimbledon, where his quest for a ninth title was ended by Hubert Hurkacz, the Pole becoming the first player to win a set 6-0 against Federer at the All England Club.

The 39-year-old's withdrawal makes him the latest tennis big name to pull out of the Tokyo Games. On the men's side, Rafael Nadal and Dominic Thiem decided against competing, while Serena Williams confirmed before her first-round retirement at Wimbledon that she had no plans to play at the Olympics.

World number one Novak Djokovic has said he is "50-50" on going for his first Olympic title. Having won all three majors so far this year, Djokovic is in prime position to become the first man to do the 'Golden Slam' in the same season. Steffi Graf achieved the feat in 1988, with a sweep of the majors followed by her victory at the Seoul Olympics.

Reigning sprint double world record holder, Usain Bolt, insists he would not be perturbed if his world records were broken with the aid of advancing athletics shoe technology.

Recently, athletics sportswear giant Nike unveiled the controversial Nike Zoom Air Viperfly spikes.  The shoe's advance design has a carbon fibre mechanism under the ball of the foot that acts like a springboard, which will generate more power in the sprinter's stride and hence lead to faster times.  The technology is geared towards helping the athlete in the last 20 metres of the race.

This version of the shoe, which has been designed specifically with 100m sprinters in mind, as it stands, will not be produced for this summer’s 2020 Tokyo Olympics.  This is due to the fact that the design currently falls afoul of the World Athletics regulations.

At some point, however, the introduction of such technology is bound to give athletes chasing the Jamaican’s marks a big advantage.  Bolt insists, however, that he has always placed more emphasis on titles in any case and would not be fretting over the records.

“I’m not going to be worried.  The fact that everyone will know why then it doesn’t bother me.  As I’ve always said, I’m happy to be the fastest man in the world but it was always the gold medals that mattered to me because that is how you really prove yourself,” Bolt told CNN.

“There are so many people that can say I am a former World record holder, but they're not a lot that can say I won three Olympic gold medals (In one event), back-to-back,” he added.

“To me, that is why I pushed myself so hard to dominate because I know at any point in time anyone can break your world record.  If you put so much emphasis on that, then what would you have left?”

Bolt’s world-leading marks of 9.58, in the 100m, and 19.19, in the 200m, have stood since 2009.  The Jamaican retired from the sport in 2017.