Elina Svitolina and Kiki Bertens, ranked fifth and seventh in the world, respectively, are the latest players to pull out of the US Open due to concerns related to COVID-19.
Svitolina, who reached the semifinals of last year's tournament, said she didn't feel comfortable traveling to the United States. The Ukrainian added that she was worried about putting her team and herself at "high risk."
Bertens, meanwhile, withdrew because she would be forced to quarantine for two weeks after returning to the Netherlands from the U.S., per regulations from the Dutch government.
That would disturb her preparations for the clay-court season, she said.
The duo join world No. 1 Ashleigh Barty in deciding to skip the upcoming competition.
The US Open is slated to begin Aug. 31 and will be played without fans in attendance at Flushing Meadows.