Novak Djokovic said Saturday he is "preparing to compete" at the US Open even though his refusal to get vaccinated will see him barred from entering the country.

Under current rules, all visitors to the United States must be fully vaccinated against coronavirus.

The Serb star, a three-time champion in New York and fresh from securing a seventh Wimbledon title, has consistently refused to take the vaccine, a stance which also saw him deported from Melbourne in January on the eve of the Australian Open.

"I am preparing as if I will be allowed to compete, while I await to hear if there is any room for me to travel to US. Fingers crossed!," wrote Djokovic on Instagram in a post accompanying a video of him training.

More than 43,000 people have signed a petition calling on the authorities to allow 21-time Slam winner Djokovic to play at the US Open which starts on August 29.

"I just wanted to take a moment and say to all of you how grateful I am to see so many messages of support and love from all around the world these days," said the 35-year-old.

"I wasn't expecting it, and that's why it feels so mindblowing. Just wanted to say THANK YOU. It feels special that people connect with my tennis career in such a loving and supportive way and wish for me to continue to compete."