Stefanos Tsitsipas says he would only get the COVID-19 vaccine if it became mandatory to compete in tennis.
The 23-year-old Greek star is among those who still have reservations about taking a vaccine, despite the men's ATP Tour publicly encouraging players to get vaccinated.
Tsitsipas reached the French Open final in June but suffered a shock, first-round exit at Wimbledon, where he told reporters he found it challenging to live and compete in the COVID-19 "bubble".
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"No one has told me anything. No one has made it a mandatory thing to be vaccinated," he told reporters, when asked if he would seek a vaccine while competing in the US.
"At some point I will have to, I'm pretty sure about it, but so far it hasn't been mandatory to compete, so I haven't done it, no."
The COVID-19 vaccine has divided opinion within tennis with world No 1 Novak Djokovic saying in April he hoped it would not become mandatory for players to compete and has declined to answer questions regarding his own vaccination status.
However, fellow 20-time Grand Slam winners Roger Federer and Rafael Nadal feel athletes need to play their part to get life back to some form of normality.
Federer said in May that he received the Pfizer-BioNTech vaccine, while Nadal said: "The only way out of this nightmare is vaccination. Our responsibility as human beings is to accept it.
"I know there is a percentage of people who will suffer from side effects, but the effects of the virus are worse.
Spectators will not be allowed to attend qualifying rounds at this month's US Open due to the pandemic, the United States Tennis Association (USTA) confirmed.
The USTA previously said it would allow full fan capacity for the main part of the tournament.
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In other news, French Open finalist Anastasia Pavlyuchenkova has withdrawn from this week's Cincinnati event due to visa issues that she hopes to have sorted out in time so she can compete in the US Open.
"Unfortunately I have to withdraw from Western & Southern Open. Still in Canada, I am waiting for my US visa," she wrote on Twitter. "Hopefully, I'll get it soon and will be there in time for the US Open."
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