Australian Open third seed Alexander Zverev has drawn attention to the relaxed COVID-19 testing policies at this year's tournament, suggesting more players could have the virus.
Zverev's comments came after his straight sets 6-4 6-4 6-0 victory over Aussie John Millman in round two.
The German was asked about Frenchman Ugo Humbert testing positive following his first-round defeat to Richard Gasquet and said he believes more players would be confirmed positive if the tournament had a tighter testing regime.
"I think this year in Australia is a lot more cases than last year, simple as that. And we are allowed to go outside to eat, allowed to do whatever we want, so I think its natural that more people get COVID," Zverev told reporters.
"I think quite a few players had it when they arrived. Quite a few players I think have it now. We are not getting tested, so I think if we would get tested there would be probably more positives than there are now, in a way."
Players are required to conduct daily rapid antigen tests but there is, for the most part, an honesty policy when it comes to reporting.
With hundreds of thousands of dollars on the line for at each stage of the tournament, it's not unthinkable to suggest a player who feels well enough might keep a positive test quiet, or simply skip a test.
Zverev said he is personally taking steps to mitigate the risk to himself as he pursues a maiden Grand Slam title.
"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. So I don't do much outside," he said.
"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."
The 24-year-old next faces Radu Albot, who defeated Aussie wildcard Aleksandar Vukic in the second round.
Zverev isn't the only player who has highlighted the Australian Open's testing policy.
During the qualifying event, Bernard Tomic told the chair umpire he was going to test positive for COVID-19 despite returning a negative rapid antigen test.
"I'm sure in the next two days I will test positive, I'm telling you," Tomic said to the chair-umpire.
"I cannot believe no one is being tested. They are allowing players to come on to court with rapid tests in their room - come on.
"No official PCR testing."
Sure enough, Tomic reported he had tested positive two days later.