In this Sept 8, 2019 photo, Rafael Nadal of Spain hits a return to Daniil Medvedev of Russia during the men's Singles Finals match at the 2019 US Open at the USTA Billie Jean King National Tennis Center in New York. (JOHANNES EISELE / AFP)

WASHINGTON - Defending champion Rafael Nadal of Spain will skip the US Open due to the spread of COVID-19 while world number one Novak Djokovic from Serbia headlines the initial men's singles entry list for the Grand Slam event, the organizers announced on Tuesday.

In last year's final, Nadal edged Daniil Medvedev of Russia 7-5, 6-3, 5-7, 4-6, 6-4 in 4 hours and 50 minutes for his fourth US Open title

"After many thoughts, I have decided not to play this year's US Open," Nadal said through social media on Tuesday. "The situation is very complicated worldwide, the COVID-19 cases are increasing, it looks like we still don't have control of it."

"We know that the reduced tennis calendar is barbaric this year after 4 months stopped with no play, I understand and thank for the efforts they are putting in to make it happen," the 19-time Grand Slam champion added.

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"All my respects to the USTA, the US Open organizers and the ATP for trying to put the event together for the players and the fans around the world through TV.

"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," the world number two said.

In last year's final, Nadal edged Daniil Medvedev of Russia 7-5, 6-3, 5-7, 4-6, 6-4 in 4 hours and 50 minutes for his fourth US Open title.

"Rafa is one of the greatest champions in our sport and we support his decision," US Open tournament director Stacey Allaster said on Tuesday.

Despite the absence of Nadal, three-time champion Djokovic will lead the men's playing field, featuring younger ATP Tour stars Dominic Thiem of Austria, last year's runner-up Medvedev and German Alexander Zverev, who will all be eying an opportunity to make their Grand Slam breakthrough.

Swiss mogul Roger Federer will also be absent from the US Open, due to two operations on his right knee this year.

In women's part, nine of the top 10 will feature the initial singles entry list. The field is led by world No 2 Simona Halep of Romania, a two-time Grand Slam champion; No 3 Karolina Pliskova of the Czech Republic; No 4 Sofia Kenin of the United States, the 2020 Australian Open champion; No 5 Elina Svitolina of Ukraine and No 6 Bianca Andreescu of Canada, the defending women's singles champion.

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No 9 Serena Williams of the United States, a six-time US Open and 23-time Grand Slam champion, will also play the major event.

The US Open is slated for August 31-September 13 at the USTA Billie Jean King National Tennis Center of New York.