World number one Novak Djokovic has cast doubt over his participation in the upcoming US Open.
The Slam is due to take place in New York in August but players will have their travel restricted and only be allowed one person with them at the court.
Djokovic has called the measures "extreme" and he thinks it'll be "impossible" on a practical level.
"I had a telephone conversation with the leaders of world tennis, there were talks about the continuation of the season, mostly about the US Open due in late August, but it is not known whether it will be held," he told told Prva TV television.
"The rules that they told us that we would have to respect to be there, to play at all, they are extreme.
"We would not have access to Manhattan, we would have to sleep in hotels at the airport, to be tested twice or three times per week.
"Also, we could bring one person to the club which is really impossible. I mean, you need your coach, then a fitness trainer, then a physiotherapist."
World number two Rafa Nadal revealed earlier this week that he's currently unwilling to travel internationally to play tournaments.