As the tournament got underway Monday, French player Benoit Paire posted an Instagram story with a graphic that said "safe environment" and added in French, "I'm fine for the moment I have no symptoms ... I hesitate to tell what really happens in this FAKE BUBBLE."
"We are confident in the health and safety plan put in place for the controlled environment at the U.S. Open," USTA spokesperson Chris Widmaier told ABC News.
Widmaier said that, based on preliminary discussions, "it was made clear that the infected player was not adhering to the health protocols that have been approved by the State of New York."
The USTA announced on Sunday that Paire tested positive for COVID-19 and is asymptomatic. He was forced to withdraw from the grand slam tournament and has been advised that he must isolate for at least 10 days.
Since Paire's positive test result, at least three players have publicly disclosed that they are now a part of USTA's Enhanced Protocol Plan for players potentially exposed to COVID-19, which involves daily testing for the virus versus every four days.
The USTA would not disclose how many players are a part of the enhanced plan, citing health privacy laws.
The 2020 U.S. Open is the first major sporting championship to be held in the U.S. since the start of the COVID-19 pandemic. Tournament organizers have been taking precautions to mitigate any possible spread of the novel coronavirus.
"Our protocol for that task was a little different than the other leagues; with all the global players and participation, we have players coming from around 60 different countries in the world," USTA CEO Mike Dowse told ABC News.
Dowse said that moving Cincinnati's Western & Southern Championship to the U.S. Open facilities in Flushing, Queens, helped create a 30-day bubble for players.
More than a dozen players pulled out of the tournament ahead of play, including Simona Halep, who is currently ranked No. 2 in the world.
At the time of her withdrawal, Halep tweeted, "After weighing up all the factors involved and with the exceptional circumstances in which we are living, I have decided that I will not travel to New York to play the US Open. I always said I would put my health at the heart of my decision."
The defending women's champion Bianca Andreescu also withdrew from the tournament. Andreescu, who hasn't played on tour since October in part because of injury, said the COVID-19 outbreak prevented her from properly preparing for competition.
Rafael Nadal also announced earlier this month that he would not seek to defend his title at the U.S. Open because of concerns surrounding COVID-19.
"The situation is very complicated worldwide, the COVID-19 cases are increasing, it looks like we still don't have control of it, Nadal wrote in an Instagram post on Aug. 4. "We know that the reduced tennis calendar is barbaric this year after 4 months stopped with no play... This is a decision I never wanted to take but I have decided to follow my heart this time and for the time being I rather not travel."
Despite the change in play, a number of top echelon players will be taking the court, including Novak Djokovic, Serena Williams, Andy Murray, Coco Gauff and Sloane Stevens.
Williams will be looking to add a seventh U.S. Open title to her portfolio and tie Margaret Court's 24 wins for the most grand slam titles ever by a woman.
"It's like I'll never be satisfied until I retire," she said on Saturday.
Arthur Ashe Stadium, the game's biggest stage and the U.S. Open's center court, will be a lot quieter than in years past. With the help of technology from IBM Watson, production teams will be able to make the empty stadium feel like the nearly 24,000 seats are full again.
IBM says it will use AI Highlights technology to recreate crowd sounds gleaned from hundreds of hours of video footage captured during last years' tournament. That technology will be featured in the ESPN broadcast of the tournament.
"This year, we made a massive pivot to use Watson AI -- underpinned by the cloud -- to bring fans closer to the action since they can't be in Flushing in person," said Noah Syken, IBM vice president of sports and entertainment partnerships.
For some players, the quiet facilities will be a throwback to the start of their tennis careers.
"I have more matches under my belt with no fans than I do with fans, so ... I think, to be honest, it will just take me back to when I first started on tour," American tennis star Coco Gauff said.
It will be a far cry from what 15-year-old Robin Montgomery could have dreamed about ahead of becoming the youngest player ever to make her debut in the main draw.
"I'm really excited to play against these top players," she told "Good Morning America," adding, "I just want to take this moment and enjoy everything about it because it's such a great opportunity. And then of course, I want to win."
During the height of the COVID-19 pandemic in New York City, the USTA transformed parts of the Billie Jean King National Tennis Center into an nearly 500-bed overflow hospital ward to help alleviate the strain on Queens' hard-hit Elmhurst Hospital.
At the start of evening sessions, the USTA will be unveiling a series of conversations called "Champions to Champions," which will honor front-line workers through the pandemic. Tennis champions like Roger Federer, Novak Djokovic, Venus Williams, Chris Evert and Billie Jean King will talk to health care workers to recognize their work in the fight against COVID-19.