Nadal, who will team with world No. 13 Paula Badosa for Spain, is headed to Sydney and will play in Group D with Australia and Britain.

Swiatek and her No. 11-ranked teammate Hubert Hurkacz from Poland will play in Group B in Brisbane with Switzerland and a yet-to-be-determined qualifier.

Top-seeded Greece, led by No. 3 Stefanos Tsitsipas and the sixth-ranked Maria Sakkari, is headed to the Western Australian state capital of Perth where they'll play in Group A with Belgium and another qualifier.

The 18-country team competition from Dec. 29 to Jan. 8 will open the 2023 tennis season ahead of the Australian Open, which begins in Melbourne on Jan. 16.

The third-seeded United States team, including No. 3 Jessica Pegula, ninth-ranked Taylor Fritz, No. 11 Madison Keys and U.S. Open semifinalist Frances Tiafoe, will play in Group C at Sydney with Germany and Czech Republic.

Rounding out the groups are France, Croatia and Argentina in Group F in Perth and Italy, Brazil and Norway in Group E in Brisbane.

Nick Kyrgios, Ajla Tomljanovic and Alex de Minaur will be among the players representing Australia. The host country was guaranteed a spot in the field.

Round-robin matches will be played in Brisbane, Sydney and Perth with each city hosting two groups of three countries before the top four _ the three group winners and the next-best placed team _ play in Sydney in the finals from Jan. 6-8.

Each squad will include up to four women and up to four men with each contest comprising four matches in singles _ two each in men's and women's _ and one in mixed doubles.

``The playing group is very excited about the United Cup, and that's confirmed in the high quality and caliber of those who've committed to the event,`` tournament director Stephen Farrow said. ``We are delighted with the depth and breadth of the teams.``

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