Novak Djokovic could risk missing several important tournaments in the U.S. over his vaccine status after officials announced extended travel restrictions for non-citizens in 2023 this week.

The 21-time Grand Slam champion recently made his way back to Australia in pursuit of his 10th title there after previously being deported from the country for not being vaccinated against COVID-19. 

Novak Djokovic returns a ball during an exhibition match

Serbian tennis player Novak Djokovic returns the ball during an exhibition match in Visoko, Bosnia and Herzegovina, on July 13, 2022.  (Nedim Grabovica/Xinhua via Getty Images)

Changes in Australian policy have allowed him to return but after also missing the U.S. Open in August, his participation in U.S. tournaments remains at risk. 

NOVAK DJOKOVIC ARRIVES IN AUSTRALIA NEARLY A YEAR AFTER COVID-19 VACCINE SAGA, DEPORTATION

The U.S. Transportation Security Administration released a letter Wednesday clarifying that any non-U.S. Citizens traveling into the States must be able to provide proof of COVID-19 vaccination, regardless of "country-by-country restrictions previously applied during the still ongoing COVID-19 pandemic" through April 10, 2023. 

The announcement extends a previous travel requirement set in October 2021. 

Novak Djokovic plays against Aljaz Bedene

Novak Djokovic of Serbia plays against Aljaz Bedene of Slovenia during the 2022 French Open at Roland Garros on May 27, 2022 in Paris, France.  (Antonio Borga/Eurasia Sport Images/Getty Images)

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"Together with the Presidential Proclamation and the CDC Order, these policies are intended to limit the risk that COVID-19, including variants of the virus that causes COVID-19, is introduced, transmitted, and spread into and throughout the United States, potentially overwhelming United States healthcare and public health resources, endangering the health and safety of the American people, and threatening the security of our civil aviation system," the emergency amendment read in part. 

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As it stands, Djokovic will miss the Indian Wells and Miami Open tournaments beginning in March.

Novak Djokovic in Madrid

FILE - Novak Djokovic, of Serbia, wipes the sweat off during a training session at the Mutua Madrid Open tennis tournament in Madrid, Spain, on April 30, 2022. (AP Photo/Manu Fernandez, File)

Djokovic has openly defended his choice not to get the vaccine, regardless of what tournaments in 2022 would allow him to compete. He competed at the French Open in May, when he lost in the quarterfinals to Rafael Nadal, and won Wimbledon for his 21st Grand Slam title.