In the past, reigning champion Rafael Nadal and the ladies' world-class Ashleigh Barty have nobbed this year's tournament in Flushing Medaows in New York.

"I understand and respect all the efforts that are made to create a safe and secure environment, but I still do not feel comfortable traveling to the United States and exposing my team and myself to risk," Ukrainian Svitolina wrote on Twitter.

Do not want to risk quarantine

Around five million Americans have been affected by the coronavirus and 160,000 people have died.

"The situation around covid-19 is still worrying and everyone's health and control over the virus is a priority," writes the Dutchwoman Bertens on Instagram.

Another reason for players from Europe to forgo the tournament is the risk of having to be quarantined for two weeks after the visit to New York. This would mean that the players will have to give up the gravel tournament in Rome and come ill-prepared for the French championships, which will be played at the end of September.

The US Open is played August 31-September 13, without an audience.