A “helpless” Iga Swiatek was left in tears after Jessica Pegula stunned the world number one Friday, with Greece’s sixth-ranked Maria Sakkari also crashing to defeat in the semi-finals of the inaugural United Cup.

Less than two weeks before the Australian Open, Poland’s Swiatek had no answers to the American’s powerful serve and searing returns, slumping 6-2, 6-2 in a deflating 71-minute defeat in Sydney.

“She played I think a perfect match, and it was pretty hard for me to find any spot where I could come back, because she really didn’t let me do that,” said Swiatek.

“I just knew that I felt kind of helpless today, because physically and mentally I wasn’t able to kind of show up even, and problem-solve,” she added of why the tears came.

“So it’s always hard when you lose, especially when you’re playing for the team and your country. So I was just sad. But, you know, it’s not the first time I cried after a lost match.”

Men’s world number 19 Frances Tiafoe then put the United States on the cusp of Sunday’s final when he swept past Kacper Zuk 6-3, 6-3. Tiafoe was initially supposed to play Daniel Michalski, but he pulled out with illness.

Italy also raced 2-0 clear in their semi-final against Greece, with a fired-up Martina Trevisan upsetting Sakkari 6-3, 6-7 (4/7), 7-5 in a gruelling 3hr 14min epic.

“Oh my God, it was a great battle today, I’m really, really happy,” said the 27th-ranked Italian who clocked one of the biggest wins of her career. “My team was incredible, they gave me a lot of energy. It was amazing.”

Trevisan’s teammate Lorenzo Musetti then crushed Greek teenager Stefanos Sakellaridis 6-1, 6-1 in the men’s singles rubber.

- High level -

With the roof closed at Ken Rosewall Arena on a rainy day in Sydney, Swiatek lost the opening seven points to be broken and go 40-0 down in the next game.

She woke up to level at 1-1, but lost focus again and was broken twice more to concede the first set in 39 minutes.

Another early break for Pegula in the second set put Swiatek on the back foot again and she had no way back against a player in scintillating form.

It was a massive blow for Swiatek ahead of the Australian Open after coming into the match as favourite following a dominant 2022 in which she beat Pegula four times, including at the French and US Opens that she went on to win.

Tiafoe was also in top form, making a quick start and never looking back.

Although Zuk provided some resistance, especially early in the second set, he was unable to stop the charging American, who is now a combined 7-0 in singles and mixed doubles at the tournament.

“My level is pretty high, it has been for a while now,” said Tiafoe. “I believe I’m playing some of the best tennis of my life, I’m just having fun out there on court.”

The final two singles matches of the semi-finals are on Saturday ahead of a mixed doubles rubber, if required.

The teams tournament began with 18 countries but has been whittled down to four after round-robin ties over six days in Perth, Brisbane and Sydney.

Poland, USA and Greece all progressed to the last four as city winners, along with “lucky losers” Italy.