“Our initial policy was that fans could bring them in but couldn’t use them to cause disruption. Yesterday we had an incident where a flag was placed on the court,” Tennis Australia said last week.
“We will continue to work with the players and our fans to create the best possible environment to enjoy tennis.”
The sport has cracked down on recognizing the two nations following the invasion of Ukraine in February, barring players from the two countries from some leading events.
Wimbledon issued a general ban on Russian and Belarusian players, while the countries are barred from participating in team competitions, including Australia’s recent United Cup.
Other global sports have gone further by banning Belarusian and Russian athletes from all competitions.
There was turmoil in some circles of Australian politics as players from the two countries took part in regular tournaments around the country this month.
Rublev and Australian Open semifinalists Karen Khachanov of Russia and Victoria Azarenka and Aryna Sabalenka of Belarus compete without their countries being recognized.
Sabalenka and Azarenka aim to become the first women from their country to face each other in what would be an all-Belarusian grand slam final.
Khachanov, who will play Greek Stefanos Tsitsipas in a semifinal on Friday night, angered Azerbaijani officials over statements related to a contentious Armenian conclave.
The Russian, who derailed Nick Kyrgios’ bid for the US Open title last September, wrote the messages on the lens of a television camera as he left the field after a fourth-round win.
For daily updates on all the tennis action at the Australian Open, sign up for our Sports newsletter here.