Argentina and Greece sweep United Cup openers

Argentina swept Spain and Greece swept Japan to open the United Cup on Friday in Perth, Australia.

Argentina's Sebastian Baez won the opening match in the mixed-team event with a 6-4, 6-4 defeat of Jaume Munar. Solana Sierra clinched the Group A win with a 6-4, 5-7, 6-0 victory over Jessica Bouzas Maneiro. To close out the day, Maria Lourdes Carle and Guido Andreozzi earned a 7-6 (6), 6-2 win in mixed doubles against Spain's Yvonne Cavalle-Reimers and Inigo Cervantes.

Argentina is hoping to advance beyond the group stage for the first time in three tournament appearances. The United States, the top seed and defending champion, is the third team in Group A.

Greece's Maria Sakkari opened Group E action with a 6-4, 6-2 win against four-time Grand Slam champion Naomi Osaka. Stefanos Tsitsipas followed with a 6-3, 6-4 win over Japan's Shintaro Mochizuki. Tsitsipas and Sakkari then completed the sweep with a 6-2, 6-3 defeat of Yasutaka Uchiyama and Nao Hibino.

Returning from a layoff for a back injury, Tsitsipas was playing his first match since September. Great Britain is the third team in Group E.

Action continues Saturday with Belgium vs. China (Group B in Sydney), Australia vs. Norway (Group D in Sydney), France vs. Switzerland (Group C in Perth) and the U.S. vs. Argentina (Group A in Perth).