SYDNEY, Australia (AFP) — World No. 9 Taylor Fritz battled past Italian Matteo Berrettini with a powerhouse performance to steer the United States to the inaugural mixed teams United Cup title in Sydney on Sunday.

Frances Tiafoe and Jessica Pegula both won their singles rubbers to give their country a 2-0 lead in the best-of-five tie with Fritz delivering victory in winning 7-6 (7/4), 7-6 (8/6).

"It's amazing for the team to win this event, we came in with really high hopes," Fritz said.

"Really happy to be in the position to clinch the match. The emotions when you win are amazing."

"We had a lot of team bonding this week," he added. "When we combine the guys and girls from the US we are so deep through the rankings it just makes team so much stronger."

A dominant United States crushed the Iga Swiatek-led Poland 5-0 to make the decider of the new tournament — which began with 18 nations playing round robin matches in Perth, Brisbane and Sydney — while Italy outgunned Stefanos Tsitsipas's Greece 4-1.

Fritz constantly put pressure on the Berrettini serve, earning four break points on his first two service games, but all were saved.

Despite the American being in charge from the baseline, it went to a first set tiebreak where he got two decisive early breaks to move 3-0 ahead before closing out the set.

Fritz again created a series of break points in the second set, but Berrettini hung on and it again went to a tiebreak where he again prevailed.

Women's world No. 3 Pegula, who burst into the top 10 in 2022 by winning the WTA 1000 Guadalajara tournament, stormed home 6-4, 6-2 against Martina Trevisan.

Tiafoe then surged through the first set 6-2 against Lorenzo Musetti before the Italian retired due to a right shoulder injury.

"Definitely very relieved, first match of the day, first match of the final," Pegula said.

"Martina is playing great, she's a fighter, I feel like she's thriving on the atmosphere with the fans and her team and really hard to beat someone like that."

"Glad I was able to play well enough to get the win."

Trevisan stunned world No. 6 Maria Sakkari in a gripping three-hour encounter on Friday, and her confidence was high.

But Pegula was also in red-hot form, toppling world No. 1 Swiatek for the first time in the semi-finals.

She came out firing against Trevisan, racing to a 3-0 lead after breaking the Italian's opening serve.

Trevisan showed the fighting qualities that helped her beat Sakkari to claw back, converting a break point in the fifth game and holding serve to get it back on level terms.