[1][2] It was originally supposed to take place with 24 teams in Brisbane, Perth and Sydney from 1 to 10 January 2021, but was changed due to the impact of the COVID-19 pandemic.

[3] Following a case of COVID-19 in the tournament's quarantine hotel, all matches scheduled for 4 February have been suspended.

[5][6] 11 countries qualified based on the ATP ranking of its highest-ranked singles player on 4 January 2021, and their commitment to play at the event.

[8][9] Switzerland withdrew after world number 5 Roger Federer was ruled unfit to compete at the event due to a knee injury.

Note: By ATP Cup rules retired match is not counting into percentage of sets and games.