Fresh off his straight sets victory over Australia's John Millman, German Olympic gold medallist Alexander Zverev raised his concerns about COVID testing at the Australian Open.
Played against the backdrop of the pandemic, the tournament has been dealing with controversies throughout the build-up, not least of all Immigration Minister Alex Hawke's decision to deport unvaccinated world number one Novak Djokovic.
Players are being relied upon to take daily rapid antigen tests for COVID-19 but questions about this policy have been raised.
Most notably when during qualifying, Australia's Bernard Tomic said PCR tests should be used, before he revealed that he later contracted COVID-19.
On Wednesday, Frenchman Ugo Humbert said he had tested positive following his round one loss to countryman Richard Gasquet.
Having breezed past Millman 6-4, 6-4, 6-0, third seeded Zverev said he believed it was likely more players in the tournament have COVID.
"We are allowed to go outside to eat, allowed to do whatever we want, so I think it's natural that more people get COVID," Zverev said at a late night press conference.
Tennis Australia has yet to comment, despite a request from Reuters.
Zverev said he was taking all precautions and staying in his own bubble to avoid infection as he chases a first grand slam title without two of the big three of men's tennis — Roger Federer and Novak Djokovic — at the tournament.
Only Spaniard Rafael Nadal remains and Zverev is seeded to face him in the quarter-finals, should things go to plan.
"I'm here to play the tournament and I understand that there is a lot of cases in Melbourne, there is a lot of cases in Australia all around," Zverev said.
"I don't do much outside, I haven't been to any restaurants yet, I haven't been out.
"I haven't been anywhere but the hotel room and the courts, so I'm kind of doing a bubble for myself, simply because I don't want to take any risks and I want to give myself the best chance possible to do well here."
Zverev next faces Moldovan qualifier Radu Albot in the third round.
ABC/Reuters
