Twenty-one time grand slam champion Novak Djokovic has announced his absence from the upcoming US Open via a Twitter post on Thursday.

Djokovic has remained unvaccinated against Covid-19 throughout the pandemic, and current US rules stipulate that any non-US citizen must be fully vaccinated against the virus in order to receive a visa and enter the country.

The 35-year-old Serbian wrote: “Sadly, I will not be able to travel to NY this time for US Open. Thank you #NoleFam for your messages of love and support.

“Good luck to my fellow players! I'll keep in good shape and positive spirit and wait for an opportunity to compete again. See you soon tennis world!”

Stacy Allaster, the tournament director of the US Open, said in a statement: “Novak is a great champion and it is very unfortunate that he will be unable to compete at the 2022 US Open, as he is unable to enter the country due to the federal government's vaccination policy for non-US citizens.

“We look forward to welcoming Novak back at the 2023 US Open.”

The US Open statement also noted that as a result of Djokovic's withdrawal taking place after the start of the qualifiers, a “lucky loser” will be included in the draw.

Djokovic was deported from Australia in January, preventing his participation in the Australian Open, due to his refusal to receive the Covid-19 vaccine.

Djokovic won tennis' most recent major at Wimbledon in July. He was unable to compete at Indian Wells or the Miami Open in March due to the same US travel regulations.

The draw for this year's US Open takes places on Thursday at noon. The tournament runs from August 29 to September 11. (CNN)

•PHOTO: Novak Djokovic returns the ball during an exhibition match in Visoko, Bosnia and Herzegovina, on July 13.