Stefanos Tsitsipas battled from a set down to topple Matteo Berrettini Saturday but it was in vain as an unstoppable Lucia Bronzetti powered Italy into the final of the inaugural United Cup against a dominant United States.

World number four Tsitsipas came through a do-or-die clash in Sydney 4-6, 7-6 (7/2), 6-4 to earn a crucial point for his country and boost his confidence ahead of the Australian Open.

But it wasn’t enough with Bronzetti pummelling Greece’s Valentini Grammatikopoulou 6-2, 6-3 in the following match to give Italy an unassailable 3-1 lead.

They meet the United States in Sunday’s final after the red-hot Americans swept past Poland 5-0.

Italy went into day two of the semi-finals with a 2-0 advantage after a gutsy Martina Trevisan upset world number six Maria Sakkari 6-3, 6-7 (4/7), 7-5 in a gripping encounter on Friday.

Trevisan’s teammate Lorenzo Musetti then crushed Greek teenager Stefanos Sakellaridis 6-1, 6-1.

With Tsitsipas winning, the pressure was on Grammatikopoulou, a late replacement for Despina Papamichail.

But she was outgunned by Bronzetti and reduced to tears in the first set.

“It’s a special moment to bring such an important point to Italy. We are a great team, great friends and I’m so excited and so happy right now,” said Bronzetti.

Berrettini, ranked 16, took a grip on his high-quality match with an unanswered break in game seven of the first set.

They went toe-to-toe in set two before the pumped-up Tsitsipas prevailed in a tiebreaker to take it to a third set where he ground down his tiring opponent.

“I hung in there and was just waiting for my chances, he’s a big server,” said Tsitsipas. “I was able to play with a lot of intensity.”

- Served well -

Earlier, a composed Taylor Fritz beat Poland’s Hubert Hurkacz in a battle of top 10 players to power the United States into the final.

The world number nine was too good for his big-serving opponent, ranked one place behind him, winning 7-6 (7/5), 7-6 (7/5).

Fritz came into the match with the United States already 2-0 up after Jessica Pegula stunned world number one Iga Swiatek 6-2, 6-2 on Friday and Frances Tiafoe swept past Kacper Zuk 6-3, 6-3.

His victory gave them an insurmountable lead before Madison Keys made it 4-0 by beating Magda Linette 6-4, 6-2.

“I think the difference in the tiebreakers was I just served well and I put some returns in the court, played some really solid points and didn’t give him anything,” said Fritz.

“I’m super excited going into the finals and I think we have been the favourites all week,” he said.

Fritz earned break points at 4-4 in set one after putting pressure on Hurkacz’s booming serve, but the lanky Pole saved them both and turned the tables to earn two set points at 5-4.

But he too was denied and it went to a tiebreak, where the American dug deep.

Nothing separated them in the second set, with Hurkacz slamming his racquet to the ground as his frustrations grew.

It again went to the tiebreak, where two unforced errors from the Pole handed Fritz victory.

Keys kept her unbeaten record at the tournament intact with a battling display against Linette.

After grinding through the first set, she went a break down in the second but was ultimately too strong.

“I feel like I’ve been playing really well on these courts and to be able to have so many matches on them already and get as comfortable as possible definitely helped me today,” said the world number 11.

Keys and Fritz then teamed up to win a dead mixed doubles rubber to ensure a clean-sweep.