The American Grand Slam faced a major setback when several top-ranked players pulled out of the tournament due to various reasons.
Nadal said because the situation with the pandemic is not under control, he did not feel it would be safe to participate.
Federer will not be playing in US Open because he is rehabbing a knee injury.
In an announcement, Kyrgios said was not attending the US Open while also bashing others who are going: "Think of the other people for once, that's what this virus is about. It doesn't care about your world record or how much money you have."
Last year's French Open champion Ashleigh Barty said she didn't feel comfortable putting herself or her team at risk.
Simona Halep decided to stay and train in Europe because she is putting "health at the heart of her decision."
Ace Naomi Osaka pays tribute to black lives in a unique fashion!
Tennis ace Naomi Osaka paid tribute to the Black Lives Matter movement uniquely. During the US Open, every round she's won so far, she made a point to honour the lives of Black people who lost their lives at the hands of police. She went on to win the Grand Slam.
Novak Djokovic's sensational disqualification
Novak Djokovic was sensationally disqualified from the US Open after striking a female lines official in the throat with a ball.
The Serbian pulled the ball from his pocket and smashed it in disgust in the direction of the official as he went 5-6 down in the first set to Spain's Pablo Carreno Busta.
The ball hit the official with a considerable force that she was left gasping and coughing. She fell in the Arthur Ashe court clutching her throat.
Djokovic rushed over to check that she was okay. He put his hand on her shoulder as she appeared to be struggling to catch her breath.
The umpire declared that Carreno Busta had won by default after a ten minutes discussion with the Serbian and rules officials.
New champion in six years
Austria's Dominic Thiem and Germany's Alexander Zverev will vie for the US Open title on Sunday in a final that will crown a new men's Grand Slam singles champion for the first time in six years.
Second-seed Thiem has lost three previous Grand Slam finals -- twice to Rafa Nadal at the French Open and once to world number one Novak Djokovic in Australia -- while Zverev had never previously been beyond the last four at a major.
With Djokovic, Nadal and Roger Federer, the sport's dominant trio, all absent from Flushing Meadows' final weekend this year, tennis will have a new Grand Slam champion for the first time since Marin Cilic beat Kei Nishikori to clinch the US Open title in 2014.
Azarenka's comeback shatters Serena's dream!
Victoria Azarenka stunned Serena Williams 1-6 6-3 6-3 in the semi-finals of the US Open on Thursday, denying the American the chance of winning a record-equalling 24th Grand Slam singles title on home soil this year.
Azarenka said her mental game had been crucial in beating the 38-year-old Williams, who needed a medical timeout to have her left ankle re-taped in the third set due to Achilles trouble.
"I have been working on finding a calm mind and keep the body going," the Belarusian said in an on-court interview. "She dug me in a big hole in the first set. I needed to find energy to climb out of the hole and it wasn't easy."
Williams, who has been stuck on 23 Grand Slam titles since winning the 2017 Australian Open, said the defeat was "obviously disappointing".
"At the same time ... I did what I could today," she added.
"I feel like other times I've been close and I could have done better. Today I felt like I gave a lot."
US Open women singles' winner
Naomi Osaka ended Victoria Azarenka's dream run to claim her second U.S. Open title in three years with a 1-6 6-3 6-3 comeback win which cemented her status as the sport's leading light both on and off the court.
Unlike the 22-year-old Japanese's first U.S. Open win in 2018 over Serena Williams, which was played in a frothing Arthur Ashe Stadium.
But the lack of buzz around the stands did not stop the two former world number ones from producing a dazzling display of shot-making.