The number of countries competing has been cut from 24 to 12 compared to last year’s inaugural ATP Cup due to the coronavirus pandemic.

After players have completed a 14-day quarantine period upon arrival in Australia, the tournament is due to run from February 1 to 5.

The 2020 edition was played across Perth, Brisbane and Sydney whereas this year’s event will be staged at Melbourne Park alongside two ATP 250-level tournaments.

Nadal’s Spain will be aiming to gain revenge over Djokovic’s Serbia after losing to them in last year’s ATP Cup final.

Reigning ATP World Tour Finals champion Daniil Medvedev headlines Russia’s team alongside fellow top 10 star Andrey Rublev, while world number three Dominic Thiem will try to take Austria to glory.

The 2021 ATP Cup is set to feature 14 of the top 15 players in the world rankings, with each team consisting of four players.

The draw is scheduled to be held on January 20 when the 12 teams will be divided into four groups of three, with the four winners advancing to the semi-finals.

"Playing as a team, for one’s country, is a rare privilege in tennis which brings the best out of our players," said ATP Cup managing director Ross Hutchins.

"This was highlighted by the incredible matches and camaraderie on display at last year’s inaugural ATP Cup.

"We would like to thank our partners, Tennis Australia, for their dedication and commitment to staging this year’s tournament, which promises to deliver a strong start to the new 2021 season.

"We cannot wait for tennis fans around the world to again share in the excitement and energy of this special event."

Qualification for the 2021 ATP Cup is based on the world ranking of each country’s top-ranked singles player, while Australia qualifies by virtue of a host wild card.

Alex de Minaur, who earned two wins over top players at last year’s ATP Cup, will once again lead the way for Australia.

"Last year we launched the global tennis season with the inaugural ATP Cup," said tournament director Tom Larner.

"It was a huge success with both players and fans, and we are excited to present the second edition in Melbourne in 2021.

"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."

The ATP Cup is among three men’s warm-up events in Melbourne ahead of the Australian Open, which has been pushed back by three weeks due to the global health crisis.

The opening Grand Slam of the year is scheduled to take place from February 8 to 21.