Defending champion Bianca Andreescu has withdrawn from this year's US Open because the coronavirus pandemic has hampered her return from injury.
The Canadian, 20, has not played since sustaining a knee injury at the WTA Finals in October.
The US Open will be held behind closed doors in New York from 31 August.
"I have made the difficult decision not to return to New York this year," said Andreescu, who beat Serena Williams in last year's final.
"I have taken this step in order to focus on my match fitness and ensure that I return ready to play at my highest level.