Novak Djokovic is unlikely to play at the US Open after organisers said they would "respect" American government rules over travel for unvaccinated players.
The US requires non-citizens to be vaccinated against Covid-19 to enter.
Djokovic is not vaccinated and missed the Australian Open earlier this year for that reason.
The 35-year-old Serb won the Wimbledon title in July and said that he would "wait hopefully for some good news".
The tournament in New York takes place from 29 August to 11 September.
Three-time US Open champion Djokovic has been named on the entry list for the final Grand Slam of the year but that is routine, rather than an indication that he will be allowed to play.
A statement from the tournament, which does not have its own vaccination rules, read: "Per the Grand Slam Rule Book, all eligible players are automatically entered into the men's and women's singles main draw fields based on ranking 42 days prior to the first Monday of the event.
"The US Open does not have a vaccination mandate in place for players, but it will respect the US government's position regarding travel into the country for unvaccinated non-US citizens."
Djokovic's win at Wimbledon took him to 21 Grand Slam titles, one behind Rafael Nadal on 22.
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