Officials taking many precautions including taking temperature every day when people walk in.
The U.S. Open also tested all the players as they arrived and then again 48 hours later.
One player, 31-year-old Benoit Paire, has tested positive and is now out of the competition.
There have only been two positives out of thousands of tests since they began. The other person was not a player.
Coordinators are working with the New York State Department of Health to approve procedures which includes a tiered bubble system since they have players coming from 60 different countries.
Tier one is with the players and anyone who has direct interaction with them. They have an exclusive hotel.
The U.S. Open will certainly have a different feel without the 50,000 daily attendees.
This year, there will be no fans.
But, it still has the promise of being the best tennis with 90 of the world's top 100 male players, seven ladies Grand Slam champions, and of course some rookies.
"So I don't know," said Serena Williams, "It's like I'll never be satisfied until I retire."
"I'm really excited to play against these top players," said Robin Montgomery, "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."
Montgomery is 15 years old and the youngest player to make her debut.
Back in March, the site had been used as a temporary hospital and a location for residents to pick up food.
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