Concerns over Iga Świątek’s fitness and form are overshadowing Poland’s breakthrough United Cup final triumph over Switzerland in Sydney.

Katarzyna Kawa and Jan Zielinski clinched Poland’s maiden title with a typically steely 6-4, 6-3 victory over Belinda Bencic and Jakub Paul in the deciding mixed doubles rubber under a closed roof at Ken Rosewall Arena.

The Swiss defeat denied Bencic a perfect 10 out of 10 for the tournament, after the tournament MVP and Tokyo Olympics gold medallist had upset an ailing Świątek 3-6, 6-0, 6-3 for a fifth consecutive singles win to go with four doubles successes with the unheralded Paul.

Hubert Hurkacz levelled the tie at one rubber apiece with a pulsating 6-3, 3-6, 6-3 victory over Switzerland’s inspired playing captain Stan Wawrinka.

The 40-year-old triple grand slam winner whipped fans into a frenzy and gestured love-heart signs to the delirious crowd after dragging his 16th-seeded Swiss underdogs to within a set of improbable Cup glory at the $17 million mixed showpiece.

Wawrinka wowed spectators as Hurkacz threatened to unravel under the crushing pressure of trying to keep the Poles in the tie.

Alas, the retiring champion wilted after nabbing the second set as Poland stormed to a first United Cup crown after losing back-to-back finals in 2024 and 2025.

But while her team rejoiced, Świątek will arrive in Melbourne with her health and game under intense scrutiny after a series of mysterious meltdowns and lacklustre showings in Sydney.

Iga Swiatek shouts during a match for Poland in the United Cup.

Iga Świątek suffered two tough losses on the weekend. (Getty Images: Brendon Thorne)

In a worrying development just a week out from the Australian Open, the world number two left the court for treatment after suffering a rare bagel in her deflating loss to Bencic.

Świątek was in state of complete despair by the end, tossing her racquet across the court and bursting into tears following her second straight defeat at the event.

World number one Aryna Sabalenka underlined her Open favouritism with a third successive Brisbane International crown on Sunday, but second-ranked Świątek’s defeat against the Swiss marked her second of the week after a straight-sets loss to world number four Coco Gauff on Saturday night.

The six-time grand slam winner was also seen crying at the first changeover during her victory over Australian Maya Joint on Friday night.

Ecstatic with Poland’s victory, Świątek played down any issues.

“Everything is fine. Just super sore,” she said.

“First tournament of the year, it causes the body [to feel] a bit different. Differently than during the season. But I had similar experience last year also, so I’ll just get good recovery, a couple of days off.

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“Also, these team events, I really love them, but they really take a lot of energy from you. So I still need to figure out how to balance that maybe in the future because I get so excited on the bench.

“It’s almost like playing a match, honestly, so, yeah, it’s all good.”

But after snaring the third leg of a fabled career grand slam with a famous 6-0, 6-0 Wimbledon final triumph last July, the state of the 24-year-old’s health and game will be among the major talking points in the countdown to the season’s first major starting next Sunday at Melbourne Park.

AAP