Grand slam giant Novak Djokovic and triple major winner Iga Swiatek will headline the second staging of the United Cup mixed teams event in Australia this summer.
Fresh off winning three of this year's four majors, Djokovic will launch his 2024 season at the United Cup as nine of the world's top 20 men feature in the 18-nation showpiece from December 29 to January 7 in Sydney and Perth.
The world No.1 and 10-time Australian Open champion will spearhead Serbia's six-strong line-up, before attempting to claim an unprecedented 25th singles slam at Melbourne Park from January 15-28.
Swiatek, dethroned as women's world No.1 in September by Aryna Sabalenka, will partner up with newly crowned Shanghai Masters champion Hubert Hurkacz in a powerful Polish outfit.
The USA will once again boast top-10 stars Jessica Pegula and Taylor Fritz in their title defence, while Greece also have a pair of top-tenners in Stefanos Tsitsipas and Maria Sakkari at their disposal.
World No.13 Alex de Minaur and three-time grand slam quarter-finalist Ajla Tomljanovic will lead an Australian team also comprising John Millman, Matt Ebden, Storm Hunter and Ellen Perez.
The other 10 confirmed nations lining up are the Czech Republic, Croatia, Canada, Great Britain, China, the Netherlands, Spain, Italy, Norway and Germany.
The United Cup, an ATP-WTA event presented in partnership with Tennis Australia, offers a minimum of $15 million in prize money plus rankings points.
Each team will consist of three men and three women, with nations to be drawn into six groups of three countries and compete in a round-robin format in Sydney and Perth.
The best-of-three ties will feature one men's and women's singles match and a mixed doubles rubber.
Perth's RAC Arena will host the first day of the United Cup on December 29, with the group stage in Sydney starting the following day.
Group winners in each city will advance to the quarter-finals, with one last-eight spot in each city awarded to the best runner-up.
The four winners will progress to the semi-finals and finals in Sydney, which will take place on January 6-7.
