World No.10 Hubert Hurkacz has put Poland on the verge of reaching Brisbane's United Cup city final after downing three-time grand slam winner Stan Wawrinka.
Hurkacz came up big in the key moments to seal the 7-6 (7-5) 6-4 victory on Tuesday evening, giving Poland a 2-1 lead against Switzerland.
The victor of the tie will top Group B and face Group E winners Italy in the Brisbane final.
World No.48 Magda Linette can secure the tie for Poland with victory over world No.35 Jil Teichmann in the second women's singles rubber.
If Teichmann wins, the tie will be decided by the mixed doubles.
Hurkacz sent down 11 aces and didn't commit a single double fault in his victory over Wawrinka.
"I've never had a chance before to play against Stan, so I was really looking forward to the match," Hurkacz said.
"I was watching him winning grand slams, so it was a huge pleasure for me to play him.
"It was very important to win that first set tiebreaker, and from there I found my rhythm on serve.
"I'm very happy to get a point for team Poland. It's a big point for us. We keep fighting."
Earlier, Matteo Berrettini beat world No.3 Casper Ruud to book Italy's spot in the Brisbane final.
The world No.16, who lost in the semi-finals of last year's Australian Open to eventual champion Rafael Nadal, used his powerful serve to dominate the Norwegian in a 6-4 6-4 win on Tuesday.
Berrettini hit 10 aces and won 88 per cent of points (35 of 40) when landing his first serve to move to 2-0 after his tournament-opening defeat of Brazilian Thiago Monteiro.
Italy went on to win the tie 5-0.
"Casper, he's a super-solid player, he improved so much in the past year, so I knew that I had to serve my best," Berrettini said.
"We know each other pretty well, so we're kind of always studying what we're doing and I knew that I had to serve like that.
"But it's one thing knowing and one (other) thing doing it."
His victory in 86 minutes put Italy up 3-0 against Norway, which was good enough for top spot in their group with two matches remaining in their tie.
The winner of the Brisbane city final will travel to Sydney for semi-finals from Friday.
"The goal is to have the longest run possible. It's super nice to play with my teammates," Berrettini said.
"The other day at dinner we were talking about when we were 12 playing against each other. It's super nice and I'm really happy. It's the first time obviously playing with the girls and I think it's special, different, maybe a little bit more stressful, but we're enjoying it a lot."
In Sydney, American Jessica Pegula eased past Germany's Laura Siegemund 6-3 6-2, with the United States going on to win the tie 5-0.
The US had already booked their city final berth against Britain a day earlier.
In Perth, Greece secured a city final when Maria Sakkari beat Elise Mertens to earn the final point they needed from the first of three chances in matches against Belgium.
The world No.6 won 6-1 7-5, following Stefanos Tsitsipas's impressive dismantling of David Goffin on Monday.
The winner of the tie between France and Croatia will advance as the other Perth finalist, with Croatia leading 2-0 after Monday's results.
