Zverev, Thiem among several top players questioning US Open protocols

Several more players have questioned whether they will play the US Open, saying they do not know whether they want to compete under the restrictions imposed due to the coronavirus pandemic. Some have also expressed safety concerns.

Alexander Zverev said that playing it would be "very difficult'' with some of the requirements.

"Everybody always wants to play a Grand Slam if it's possible," Zverev told press at Novak Djokovic's Adria Tour Belgrade event, before adding, "You have to stay stay two weeks in quarantine at JFK, you're not allowed to go basically anywhere, and you need to come in advance. Because two weeks of quarantine, you're not going to be able to play a tournament straightaway, so you have to have another two weeks of training.

"For Cincinnati, and the US Open, it's going to be the same thing. So we're basically we're counting six, seven weeks of staying at JFK airport, and the tennis stadium."

Zverev also mentioned the lack of fans and only being allowed to bring one person with them to the event, along with other changes.

"We will not be able to use locker rooms, no showers on site, no food on site," he said. "I don't think a lot of people will feel comfortable."

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Fellow Top 10 player Dominic Thiem also had similar concerns.

"I agree. All these circumstances are pretty tough," said Thiem, who is also playing the Belgrade event. "To be only able to take one person—a Grand Slam can be pretty demanding physically, and choosing whether to take your coach or physio... I think some circumstances would have to change to make sense to go there."

Grigor Dimitrov was unsure if he would play as well. "Honestly, there is not much to say right now," he said. "I know they're pushing really hard but it needs to be safe, it needs to make sense for the players."

Top-ranked Djokovic has already spoken of the "extreme" restrictions and indicated that he does not want to play under such conditions.

Nick Kyrgios and John Millman have argued that it would be unsafe to hold the tournament.

But Richard Gasquet appeared more willing to consider competing. "The conditions are difficult, but feasible," he toldAFP. "You arrive there, you go to your hotel, you stay in your room. It's normal, it's to protect others and yourself."

Simona Halep and Petra Kvitova have expressed doubts, joining No. 1 Ash Barty in saying she has not decided yet.

"It would not be an easy transition," Halep told the New York Times. ''Especially on our bodies."

Some players, like Danielle Collins and Dan Evans, have called for Djokovic and others to play if the tournament is held.

Officials are expected to decide next week whether to hold the US Open. The ATP and WTA tours will also announce whether any of the scheduled warmup events, including a relocated Cincinnati, will be played.