The United States beat Italy 3-0 to win the inaugural mixed teams United Cup.
World number nine Taylor Fritz secured the title with a 7-6 (7-4) 7-6 (8-6) victory over Matteo Berrettini in the best-of-five matches final in Sydney.
Earlier, Jessica Pegula beat Martina Trevison 6-4 6-2 before Lorenzo Musetti withdrew from his men's singles rubber against Frances Tiafoe with a shoulder injury after losing the first set 6-2.
"I was happy to be in that position to clinch the match," said Fritz.
"It's amazing for the team to win this event, we came in with really high hopes.