Australian tennis star John Millman sparked a fierce Twitter row with comments made about America's COVID-19 rules.
The Aussie tour veteran suggested it was rich for the States to lock out Novak Djokovic over his vaccination status, while so many Americans seemingly struggle to abide by the laws themselves.
America requires tourists from outside the country to be vaccinated against COVID-19 before they can enter.
The law means Djokovic is not able to compete at the US Open, which begins later this month. The Serbian champion was booted out of Australia at the start of this year for the same reason.