Novak Djokovic is unsure about his tennis future this year.

Following his Wimbledon victory on Sunday, the 21-time grand slam winner said he doesn't know if he will be allowed to play in the U.S. Open.

Djokovic is not vaccinated against COVID-19, which is a requirement for foreigners entering the U.S.

"I'm not vaccinated and I'm not planning to get vaccinated so the only good news I can have is them removing the mandated green vaccine card or whatever you call it to enter United States or exemption," Djokovic said.

The tennis star added that he didn't know what type of exemption he would be potentially eligible for, so he will wait to see if the U.S. allows him to enter the country.

Djokovic was invited to play in the Australian Open earlier this year, but had his visa stripped when the government said his exemption didn't meet the country's requirements for unvaccinated visitors. Djokovic was held in an immigration holding facility until he was kicked out of the country.

He was allowed into France for the second grand slam of the season. He lost in the quarterfinals to Rafael Nadal, who went on to win the tournament.