World No.2 Simona Halep is the latest big name to pull out of the US Open.
Halep, a two-time Grand Slam champion, has opted to stay in Europe amid fears over coronavirus and becomes the sixth member of the top 10 to withdraw.
The tournament in New York gets under way at Flushing Meadows on August 31, just days after the Western & Southern Open is held at the same site.
Halep said on Twitter: "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 @usopen.
"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 @usta and @WTA have worked tirelessly to put on a safe event and I wish everyone there a successful tournament."
Halep joins defending men's champion Rafael Nadal, reigning women's champion Bianca Andreescu and women's World No.1 Ashleigh Barty in not playing the tournament.
The Romanian, who won a WTA tournament in Prague over the weekend, is opting to stay and train in Europe ahead of the clay-court swing, which commences immediately after the US Open.
Her withdrawal is another blow to tournament organisers, who have seen a raft of high-profile names pull out of the Grand Slam.