Djokovic's Serbia and Nadal's Spain will compete against Austria, Russia, Greece, Germany, Argentina, Italy, Japan, France, Canada and Australia in the 12-team competition, as per an ATP media release.
Top ranked tennis players Novak Djokovic and Rafael Nadal will lead the field for the upcoming 2021 ATP Cup scheduled to be played at the Melbourne Park from February 1 to 5.
Djokovic's Serbia and Nadal's Spain will compete against Austria, Russia, Greece, Germany, Argentina, Italy, Japan, France, Canada and Australia in the 12-team competition, as per an ATP media release.
Qualification for the tournament is based on the ATP ranking of each country's top-ranked single player, while Australia qualifies by virtue of a host wildcard.
"Last year we launched the global tennis season with the inaugural ATP Cup. It was a huge success with both players and fans, and we are excited to present the second edition in Melbourne in 2021," said ATP Cup Tournament Director Tom Larner.
"The players are looking forward to stepping up and representing their countries again, and the field, including defending champions Serbia and finalists Spain, is strong. This is a format that shows off the passion of the players and we're expecting some spectacular tennis action," he added.
The 2021 ATP Cup will feature 14 of the top 15 players in the ATP rankings. Each team will consist of four players per country.
Reigning Nitto ATP Finals champion Daniil Medvedev headlines Russia's team alongside fellow top 10 star Andrey Rublev, and world number three Dominic Thiem will try to take Austria to glory. Rising star Alex de Minaur will once again lead the way for Australia.
The draw for the 2021 ATP Cup will take place on January 20, when the 12 teams will be divided into four groups of three for group stage, round-robin play. The four group winners will advance to the semi-finals.
The inaugural ATP Cup was played in Brisbane, Perth and Sydney in 2020 when Serbia defeated Spain 2-1 in a thrilling championship clash, which included a tantalising match-up between Djokovic and Nadal.
Due to the Covid-19 pandemic, major tennis events have been relocated to Melbourne this year.
