Defending champion Rafael Nadal said on Tuesday he will not play the US Open, citing concerns over the coronavirus and slamming tennis's "barbaric" revised calendar.
"After many thoughts I have decided not to play this year's US Open," Nadal said on Twitter.
"The situation is very complicated worldwide, the Covid-19 cases are increasing, it looks like we still don't have control of it.
"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 34-year-old Spanish star also took aim at the international tennis schedule, which has been revised following disruptions sparked by Covid-19 shutdowns.
The US Open in New York, scheduled for 31 August through 13 September, will be followed a fortnight later by the French Open at Roland Garros.
"We know that the reduced tennis calendar is barbaric this year after four months stopped with no play..." Nadal said.
With Nadal's long-time rival Roger Federer already ruled out of the tournament as he recovers from knee surgery, the US Open will mark the first time since 1999 that neither player has featured in the main draw of a Grand Slam event.
Nadal, who has 19 Grand Slam victories, could have equalled Federer's tally of 20 Slam wins in New York.
Doubts about Nadal's willingness to play the US Open have swirled for months as tennis grapples with a calendar that has been decimated by pandemic disruption.
In June, Nadal warned he would not consider playing the US Open unless he was satisfied conditions were "completely safe."
Nadal's name was entered last week on the US Open tune-up tournament, the ATP/WTA Western and Southern Open, which will be held in New York this year instead of Cincinnati.
However Nadal had long harboured concerns over the proximity of the US Open and the swing of clay court events scheduled through September.
Nadal's uncle and long-time former coach, Toni, said in June that the former world No 1 was uncertain about which events he would play.
"The schedule is unrealistic, especially for veteran players, who cannot compete for so many weeks in a row," Toni Nadal said. "I think it is a bit ugly what the ATP has done."
With Nadal and Federer missing from New York, world No 1 Novak Djokovic will have a golden opportunity to land an 18th Grand Slam singles title.
Djokovic was named on the US Open entry list on Tuesday which included seven of the world's top 10 players.
Djokovic, a three-time US Open champion, will be joined by world No 3 Dominic Thiem, world No 5 Daniil Medvedev and sixth-ranked Stefanos Tsitsipas.
The women's entry list meanwhile includes 13 Grand Slam champions and nine of the world's top 10 players.
With Australia's world No 1 Ashleigh Barty withdrawing from the tournament last week, citing "significant risks" from Covid-19, the women's draw will be led by Romania's world No 2 Simona Halep of Romania, a two-time Grand Slam champion.
Serena Williams is also in the field, chasing a seventh US Open and 24th Grand Slam time overall.
After many thoughts I have decided not to play this year’s US Open. The situation is very complicated worldwide, the COVID-19 cases are increasing, it looks like we still don’t have control of it.— Rafa Nadal (@RafaelNadal) August 4, 2020