Novak Djokovic, one of the world’s most prominent sports stars to hold out against getting a coronavirus vaccination, was included in the field for this week’s Indian Wells tennis tournament in Southern California, even though there are doubts over whether he will be able to enter the United States and participate.

Djokovic was deported from Australia in January after immigration officials there ruled that he was a danger to society because they said he could energize the country’s anti-vaccination movement. He was thus unable to defend his Australian Open title, which he has won a record nine times.

Djokovic has expressed reluctance to be vaccinated against coronavirus, saying that he was not convinced by the science. He said the issue was more important to him than adding to the 20 Grand Slam tournaments he has won.

Djokovic told Australian border officials in January that he was unvaccinated, and in recent interviews has given no indication that his status has changed.

Djokovic’s name and picture appeared on a list of players in the main draw for the BNP Paribas Open, which starts on Wednesday at the Indian Wells Tennis Garden. Although not one of the sport’s four Grand Slams, the hard-court event is considered one of the biggest tournaments in the world.

Djokovic, the tournament’s second seed, has a bye in the first round, so he is not scheduled to play until Saturday.

Under U.S. immigration law, people who are not citizens and also not immigrants must show proof of full vaccination as well as a negative Covid test to enter the country by air.

Djokovic spent two years as the game’s No. 1 ranked player until February, when he slipped to No. 2.

In his absence, Rafael Nadal won the Australian Open and moved one ahead of his rival as the men’s player with the most Grand Slam wins. Nadal also is listed among the players at Indian Wells, although Roger Federer, who has also won 20 Grand Slam titles, is not.