Novak Djokovic has withdrawn from Indian Wells and the Miami Open - the first two Masters Series events of the year - because of US coronavirus rules.
Regulations require any non-US citizen to have a Covid vaccination before entering the country.
Serb Djokovic, 34, told the BBC last month that he had not been vaccinated.
The 20-time Grand Slam winner was included in the draw for both events, but has since posted on Twitter that he knew it was "unlikely" he could travel.
More to follow.