The head of an exhibition tennis tournament in Berlin says she has doubts the US Open will go ahead at the end of August as planned amid the coronavirus pandemic.
"I think it is realistic that the ladies' tour will start in Europe at the beginning of August as planned," Barbara Rittner, captain of Germany's Fed Cup team and director of this week's Berlin tournament told newspaper Berliner Morgenpost.
"But in view of the immensely high numbers of infections throughout America, I don't see the US Open taking place in New York at the end of August, mainly because the travel restrictions are high.
"As a player, I wouldn't want to fly there."
Amid the Covid-19 pandemic, the United States is the hardest-hit country in the world, with around 135,000 deaths and more than 3.2 million confirmed cases.
By comparison, Germany currently has 200,260 cases and 9,078 deaths due to the virus.
Hygiene has been strictly observed at this week's Bett1Aces exhibition tournament in Berlin, which Rittner is overseeing.
The event is being used as a model for the ATP and WTA, the men's and women's tennis tours respectively, which are due to next month.
The women's WTA tour is scheduled to restart on August 3 in Palermo, Italy, followed by a tournament in Prague, with a separate tournament in New York before the US Open starts on August 31.
The men's ATP tour resumes in mid-August with a tournament in Washington before the US Open.
Spectators and players in Berlin had their temperatures monitored and upon arrival, had to walk through a machine which sprays them with disinfectant.
The extra hygiene measures reflected in the ticket price of 120 ($136) to 150 euros with the daily crowds well under the 1,000-capacity at the Steffi Graf Stadium in west Berlin.
"So far, everything has gone smoothly. You really have to compliment the players and their teams," added Rittner.
After his victory on grass in the rain-affected men's final on Wednesday, world number three Dominic Thiem is the favourite for the hard court event which starts Friday in a hanger at Berlin's Tempelhof Airport.
Thiem beat Italy's Matteo Berrettini 6-7, 6-4, 10-8 in Wednesday's final on grass and earlier in the week said he felt the US Open is on "shakey legs".
Berrettini struggled when asked if he thinks the men's season will resume in the USA.
"That's a tough question," said the Italian ranked eighth in the world.
"If it's not safe for me and my team, we will not go there. But there is still some time left."