Coco Gauff of the United States, right, after defeating Shuai Zhang of China in their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Taylor Fritz and Coco Gauff of the United States talk between point against Petra Marcinko and Ivan Dodig of Croatia during their United Cup mixed doubles tennis match in Perth, Australia, Tuesday, Dec. 31, 2024. (AP Photo/Trevor Collens)

Shuai Zhang of China hits a return shot to Coco Gauff of the United States during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Elena Rybakina of Kazakhstan serves to Laura Siegemund of Germany during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Elena Rybakina of Kazakhstan hits a return shot to Laura Siegemund of Germany during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Coco Gauff of the United States serves to Shuai Zhang of China during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Daniel Masur of Germany hits a return shot to Alexander Shevchenko of Kazakhstan during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Taylor Fritz and Coco Gauff of the United States laugh as they celebrate defeating Petra Marcinko and Ivan Dodig of Croatia in their United Cup mixed doubles tennis match in Perth, Australia, Tuesday, Dec. 31, 2024. (AP Photo/Trevor Collens)

Alexander Shevchenko of Kazakhstan, right, shakes hands with Daniel Masur of Germany after winning their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

El alemán Alexander Zverev celebra un punto crucial ante el chino Zhizhen Zhang en la United Cup en Perth, Australia el lunes 30 de diciembre del 2024. (AP Foto/Trevor Collens)

Alexander Zverev of Germany, center, talks to his replacement Daniel Masur, left, during a break in Germany's quarter final match against Alexander Shevchenko, after Zverev pulled out with a bicep injury from the United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Alexander Shevchenko of Kazakhstan hits a return shot to Daniel Masur of Germany during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)

Elena Rybakina of Kazakhstan hits a return shot to Laura Siegemund of Germany during their United Cup tennis match in Perth, Australia, Wednesday, Jan. 1, 2025. (AP Photo/Trevor Collens)