Elina Svitolina and Kiki Bertens have become the latest major names to withdraw from this year's US Open.
The world's no. 5 and 7 women's tennis players have joined world no.1 Ashleigh Barty in making themselves unavailable for the New York Grand Slam.
When the US Tennis Association released its entry list earlier this week, the women's field appeared relatively untouched by fears of COVID-19.
At the time Barty was the only one of those in the WTA top 10 to withdraw.
This year's US Open is due to get underway at Flushing Meadows - behind closed doors, and under strict medical protocols - on August 31.
Svitolina - a Wimbledon and US Open semi-finalist last year - thanked the organisers for managing to stage the tournament, but confirmed she wouldn't be there.
— Elina Monfils (@ElinaSvitolina) August 7, 2020
"I understand and respect all the efforts they are putting to make it happen in a safe environment," she wrote, "But I still don't feel comfortable to travel to US without putting my team and myself at high risk."
Bertens would have to travel from her native Netherlands, and so would be required to quarantine for 14 days before striking a ball in anger.
She's hopeful to be able to play what's left of the clay court season, which will culminate with a delayed French Open from September 27.
Writing on Instagram, she said, "The situation around COVID-19 is still that worrying and the health of everyone and the control over this virus is priority.
"Our prime minister indicated yesterday that we should be quarantined for 14 days after coming back from the States.
"Of course we respect this as a team and this would disturb our preparation for my beloved clay court tournaments in Rome and Paris.
"I hope the situation will soon take a positive turn and wish everyone good health. Take care!
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