John McEnroe, the former Tennis great, said it would be "a joke" if Novak Djokovic is unable to compete at the tournament due to his COVID-19 vaccination status.
Djokovic has declined to get vaccinated and appears set to miss out on the year's last Grand Slam because of the current U.S. rules that need travellers to show proof of full vaccination to board flights to and enter the United States.
The Serbian had said he had no issues missing Grand Slam tournaments that require participating tennis players to be vaccinated. Djokovic remains on the entry list for the Aug. 29 to Sept. 11 tournament in New York.
"I don't think it's fair," McEnroe, who works as a tennis analyst for ESPN, told reporters Tuesday. "I think it's a joke. I would have had the vaccine and gone and played, but he's got very strong beliefs and you have to respect that.
"At this point, in the pandemic, we're 2½ years in, I think people in all parts of the world know more about it, and the idea that he can't travel here to play, to me is a joke."
Djokovic had taken part in last year's US Open, where he finished runner-up to Daniil Medvedev, but he was not able to compete in the Australian Open this year after being deported from the country over his vaccination status in January.
When quipped about Djokovic's chances of finishing above his rivals in terms of Grand Slam victories being affected by his absences from major tournaments, McEnroe said, "that's the question that we all want to know the answer to."
"Obviously, Rafa Nadal has benefited from that. If a guy has won the Australian Open eight or nine times, you would think
"These three guys are already above everyone else. Rafa was able to pull off a miraculous win that not many people expected in Australia. Novak got there at Wimbledon and then Rafa got hurt."