The French Open which has been pushed back from May to a 27 September start, could host up to 11,500 spectators per day.
US Open 2020: World No 2 Simona Halep latest in list of stars to pull out of tournament over COVID-19 fears
Halep joins a host of top players who are passing on playing at Flushing Meadows when the next Grand Slam tournament begins on 31 August.
Romania's Halep, the 28-year-old reigning Wimbledon champion and world number two, beat the 23rd-ranked Mertens 6-2, 7-5 in an hour and 33 minutes.
Prague Open 2020: Simona Halep sets up final with Elise Mertens after beating compatriot Irina-Camelia Begu
Halep won 7-6 (7/2), 6-3 in an hour and a half to set up a final clash against 23rd-ranked Belgian Elise Mertens, who beat Czech Kristyna Pliskova 7-5, 7-6 (7/4) in the other semi-final on Saturday.
Halep needed only 59 minutes to beat the 22-year-old Pole 6-2, 6-0 in what was her first convincing win at tournament following two tight three-setters.
Prague Open: Simona Halep recovers from opening set loss to reach quarter-final; Eugenie Bouchard beats Tamara Zidansek
Simona Halep next faces Magdalena Frech after the 174th-ranked Pole defeated Arantxa Rus 6-3, 2-6, 6-4 to make her first career quarter-final.
It was the first competitive match for Halep since she won the Dubai Championships in February for her 20th career WTA title.
Ashleigh Barty has said she is skipping the US Open amid the virus spread, just like Kiki Bertens, Elina Svitolina or Rafael Nadal, and Simona Halep said she will make a decision on her participation soon.
Simona Halep withdraws from Palermo Ladies Open due to quarantine order from Italy's health ministry
Second-ranked Simona Halep withdrew from the Palermo Ladies Open Sunday following a quarantine ordinance issued by Italy’s health ministry.
Italian Health Minister Roberto Speranza said on Friday people who have been in Romania and Bulgaria in the past 14 days will be quarantined upon arrival in Italy, a move aimed at preventing the importation of COVID-19 cases.
In Palermo there would be strict health protocols for players and the number of spectators at the 1,500-seat centre court would be restricted to 350.
The 28-year-old Halep has not played since her win over Kazakhstan’s Elena Rybakina in the final of the Dubai Duty Free Tennis Championships on 22 February.
'Something just doesn’t feel right': Canadian tennis player Gabriela Dabrowski criticises decision to go ahead with US Open
Gabriela Dabrowski feels that despite strict health protocols it will be 'impossible' to protect players in a bio-secure bubble throughout US Open
US Open 2020: World No 1 Simona Halep 'highly unlikely' to feature in Grand Slam with 'incredibly difficult' protocols in place
The United States Tennis Association (USTA) received the green light to hold their marquee tournament in New York as scheduled from 31 August - 13 September without fans.
Kyrgios, who has been in lockdown in Australia since the pandemic brought a halt to the ATP Tour, appeared more concerned about having to undergo 14 days of self-isolation upon his return home from Flushing Meadows.
World No 1 Ashleigh Barty joins list of high-profile players expressing concerns over US Open timing
Ash Barty has joined the ranks of high-profile players concerned over the staging of the US Open while there’s still so much uncertainty around the coronavirus pandemic.
Financial aid has slowly trickled in for tennis players in the lower echelons of the sport during the COVID-19 shutdown but the vast majority of men and women who coach them for a living have been left to fend for themselves.
Cahill said organisers were considering flying players to New York from around the world on charter flights and keeping them in an isolation bubble with regular testing for COVID-19.
Simona Halep's coach Darren Cahill backs idea of WTA-ATP merger, says idea would make tennis 'simpler'
Cahill said, 'I think, hypothetically, it would be a pretty good position for a tennis player to be in, because you know that every single decision being made is made in the best interest of the game.'
Wimbledon champion Simona Halep is recovering well from a foot injury she suffered in February and is able to run without pain, the former world number one has said.