The US Open is scheduled to begin on Aug. 31 in New York, but as that date approaches, more tennis stars are withdrawing from the event. On Friday, two of the best women's players in the world, Elina Sviotlina (ranked No. 5) and Kiki Bertens (ranked No. 7) announced that they won't be participating in the US Open due to COVID-19 concerns.

"Considering all the aspects, I have decided not to play the US Open 2020," Svitolina said in a statement on her Twitter account."I want to thank the USTA, organisers and WTA for giving the players a chance to play and the fans to watch this great event. I understand and respect all the the efforts they are putting to make it happen in a safe environment, but I still don't feel comfortable to travel to US without putting my team and myself at high risk."

Bertens echoed Svitolina's thoughts about not being "comfortable" traveling to the United States right now in her own statement.

"The situation surrounding COVID-19 is still so worrying that everyone's health is paramount and control of this virus is of course a priority," Bertens, who is from Netherlands, said. "Our Prime Minister also indicated yesterday that we should be quarantined for two weeks after America."

The Grand Slam tournament is scheduled to be played in a bubble in Queens with strict safety protocols. Even with the extra precautions, Svitolina and Bertens join the top-ranked women's player in the world, Ashleigh Barty, in not wanting to come to the United States for the event.

The same goes for many of the biggest names in men's tennis.

Defending champion Rafael Nadal announced on Tuesday that he doesn't feel safe traveling during the pandemic and won't be participating in the tournament. In addition, Australian Nick Kyrgios is sitting the event out.

Novak Djokovic and Serena Williams are currently on the list of expected participants at the US Open, which is scheduled to take place from Aug. 31 to Sept. 13.