The United Cup, a mixed-team tennis competition, begins its fourth edition with matches in Perth and Sydney. On opening day in Perth, Spain faces Argentina, featuring singles matches between Jaume Munar and Sebastian Baez, and Jessica Bouzas Maneiro and Solana Sierra, with mixed doubles deciding ties. Greece will also play Japan, with Maria Sakkari meeting Naomi Osaka and Stefanos Tsitsipas facing Shintaro Mochizuki. The tournament involves 18 national teams competing in a group stage followed by a knockout format.