Rafael Nadal and Nick Kyrgios could face off in the inaugural United Cup, while WTA world number one Iga Swiatek will represent Poland.

The United Cup is the new warm-up tournament for the ATP and WTA Tour seasons, and will take place in Australia in December and January.

While ATP world number one Carlos Alcaraz will not feature, compatriot Nadal will be competing for Spain, and they have been drawn alongside Australia and Great Britain in Group D.

Those matches will be played in Perth, with a clash between Nadal and Kyrgios, who have enjoyed an entertaining rivalry down the years, in the offing.

They were set to meet in the semi-finals at Wimbledon this year, but Nadal withdrew due to injury, handing Kyrgios a walkover into his first grand slam final, which he lost to Novak Djokovic, who will not be playing in Australia.

Serbia are not among the batch of teams taking part, but even so, there remains doubt whether Djokovic would be able to enter Australia given his stance against the COVID-19 vaccine, which eventually saw him deported from the country after a drawn-out legal battle ahead of this year's Australian Open.

Emma Raducanu has decided against playing for the British team, which also does not feature Andy Murray.

Casper Ruud, the beaten US Open finalist, will play for Norway in Group E, in Brisbane, while Alexander Zverev will be in action for Germany.

Swiatek is the biggest name from the WTA Tour to enter, with the brilliant 21-year-old lining up alongside Hubert Hurkacz for Poland in Group B.

Maria Sakkari and Stefanos Tsitsipas, along with his brother Petros, will team up for Greece in Group A.

Two more countries will be admitted to the tournament later in November.