All the entry regulations in reference to the Corona Vaccination are lifted in the USA at 11 May. This will allow Djokovic to play at the US Open and chase another Grand Slam title. However, it is not certain whether he will remain number 1 in the world rankings. In any case he will not be allowed to play at the tournaments in Indian Wells and Miami. So his pursuers have two possibilities to get closer to him or even to regain spot number 1.