World Number two Simona Halep of Romania announced on Monday that she has pulled out of the 2020 US Open due to COVID-19.
"After weighing up all the factors involved and with the exceptional circumstances in which we are living, I have decided that I will not travel to New York to play the US Open," Halep said through social media.
"I always said I would put my health at the heart of my decision.
"And I therefore prefer to stay and train in Europe. I know the United States Tennis Association and Women's Tennis Association have worked tirelessly to put on a safe event and I wish everyone there a successful tournament," added Halep, who just won the Prague Open title on Sunday.
Six of the top eight women in the WTA rankings won't play in New York, including world number one Ash Barty of Australia and defending champion Bianca Andreescu of Canada.
No. 5 Elina Svitolina from Ukraine, No. 7 Kiki Bertens of the Netherlands and No. 8 Belinda Bencic of Switzerland also pulled out of the US Open.