Naomi Osaka admits the risks of holding the Tokyo Games amid the raging COVID-19 pandemic should continue to be carefully discussed.
Tokyo is under a state of emergency until the end of May due to a rise in coronavirus cases, while surveys have shown that most Japanese oppose holding the Games this summer due to worries about the virus.
Osaka, the world No 2 and one of Japan's top athletes, said staging the Games should remain a topic of discussion as long as the subject was "making people very uncomfortable".
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"Of course I want the Olympics to happen, but I think there's so much important stuff going on, especially the past year," she said. "A lot of unexpected things have happened.
"For me, I feel like if it's putting people at risk... then it definitely should be a discussion, which I think it is as of right now. At the end of the day, I'm just an athlete, and there is a whole pandemic going on."
Japan's Prime Minister Yoshihide Suga has promised to fast-track the government's vaccination drive, saying it aimed to administer 1 million shots a day.
Osaka, who has won both the US Open and Australian Open twice, said she had already been vaccinated against COVID-19, and added that it would not be right to "force" people to get inoculated.
"There is going to be a lot of people entering the country so they definitely have to make the right decisions on that," she said.
"I've gotten vaccinated (but) I think that at the end of the day you can't force anyone to be vaccinated."
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Japan has recorded more than 600,000 coronavirus cases and more than 10,500 deaths, but its inoculation campaign has been relatively slow so far, with only about 2 per cent of the population of about 126 million having received at least one vaccine dose.
The International Olympic Committee (IOC) recently announced that vaccine developers Pfizer and BioNTech would donate doses to inoculate athletes and officials preparing for Tokyo.
The IOC has repeatedly said the 2020 Olympics - postponed by a year due to the pandemic - were being organised as if the vaccines were not available, but has pushed hard to get athletes vaccinated.
Nishikori wary of Covid-19 threat at Athletes' Village
Osaka's compatriot Kei Nishikori also expressed concerns about the threat of coronavirus transmission at the Athletes' Village in his home country.
"This is not like 100 people like these tournaments," Nishikori said at the Italian Open in Rome on Monday.
"It's 10,000 people in a Village, playing a tournament. I don't think it's easy, especially (with) what's happening right now in Japan, it's not doing good."
Nishikori won bronze in the men's singles at the 2016 Olympics in Rio.
"You can make a good bubble and maybe you can do it," he added. "There is some risk too. What happens if there's 100 cases in the Village? Or it can be thousands."
Several test events with foreign athletes have been successfully held, most recently on Sunday, but a visit by International Olympic Committee head Thomas Bach scheduled for May 17-18 has been cancelled.
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