Andy Murray says players have a responsibility to the public as they travel around the world, and should therefore be vaccinated against Covid.
Many are reluctant to take the vaccine, and tournaments are yet to make it a condition of entry.
But with spectators at the US Open having to show proof of at least one vaccination dose, there is an increasing focus on the players.
"I'm hoping that more players choose to have it in the coming months," he said.
Speaking before Monday's first-round match with Stefanos Tsitsipas, Murray added: "Over the next few months things are going to probably end up changing quite a bit.