Novak Djokovic has spoken out amid the debate surrounding the COVID-19 vaccine, saying he hopes it does not become compulsory for tennis players to be inoculated.
The World No.1 has previously spoken out against vaccines and insisted any decision he makes on whether or not to take the COVID-19 jab will remain private.
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"I am still a supporter of freedom of choice," Djokovic said after reaching the semi-finals of the ATP tournament in Belgrade.
It was in the Serbian capital last summer where Djokovic, as well as a number of other players, tested positive for COVID-19 after organising a controversial exhibition event.
On whether or not he will be vaccinated to guarantee entry to tournaments, 33-year-old Djokovic refused to commit himself.
"I will keep my decision to myself, I think it's a private, intimate thing," he said.
"I do not want to be labelled as someone who is for or against vaccination.
"I hope it does not become compulsory."
Djokovic's comments came just 24 hours after Ash Barty revealed she has already received the vaccine.
The women's World No.1 was one of several players to receive the vaccine through a WTA Tour initiative at a tournament in South Carolina earlier this month.
Barty and her Australian coach Craig Tyzzer were among those who took advantage of the WTA's offer, but said she made sure they were not "jumping the queue".
"We were looking at different avenues to try and get vaccinated without jumping the queue in Australia to see what our options were, and we weren't able to get much of an answer before we left in March," she told reporters at a tournament in Stuttgart.
"We were able to get the vaccine, as were a lot of other players, through the Tour and that they had organised through a certain pharmacy that had extras, and that was important to me knowing that those who were the most vulnerable were able to get it first."
Barty spent the last year back home in Australia, mostly due to the COVID-19 pandemic, and the Miami Open was her first tournament abroad since February 2020.
Novak Djokovic reaches semi-finals at Serbia Open
On court, Djokovic stayed on course for a third Belgrade title with a comfortable 6-1, 6-3 quarter-final win over compatriot Miomir Kecmanovic.
Djokovic, the 2009 and 2011 champion at the event which is played at a venue which carries his name, will face Russia's Aslan Karatsev for a place in the final.
In their first meeting, Djokovic broke his 21-year-old opponent's first service game and repeated the feat for a 5-1 lead in the opener.
His only blip was when he was broken as he served for the match at 5-2 in the second set.
However, it was a brief respite for World No.1 47 Kecmanovic who handed back the break in the next game allowing the top seed to complete a 75-minute win.
"I think personally I'm feeling very well on court, moving well, hitting the ball well and, of course, enjoying the home court advantage," Djokovic said.
"So I'm really excited to go out in the semi-finals on the court again tomorrow."
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