Novak Djokovic is once again set to miss Indian Wells and the Miami Open after the United States extended the entry requirements for international travellers to be vaccinated against Covid-19.Indian Wells and the Miami Open begin on 6 March and 20 March respectively but, despite the relaxing of Covid rules in many countries around the world, proof of vaccination against Covid-19 will be required in the US until at least 10 April.It remains uncertain whether US vaccination requirements will be relaxed in time for Djokovic to compete in the US Open, which begins at the end of August. Indian Wells and the Miami Open are considered two of the most reputable tournaments of the year outside of the …