Germany overcame host Australia in a late-night semifinal thriller here on Saturday to book a showdown with Iga Swiatek's top-seeded Poland in the mixed teams United Cup.
After the singles matches were split, Germany's Alexander Zverev and Laura Siegemund beat Matthew Ebden and Storm Hunter 7-6 (2), 6-7 (2), 15-13 in a deciding mixed doubles contest that finished at 2:20 a.m. local time on Sunday.
Germany will face a tough task of backing up for Sunday night's final against favorite Poland.
Poland underlined their title credentials by sweeping France with Swiatek overpowering Caroline Garcia 4-6, 6-1, 6-1 after Hubert Hurkacz, ranked a career-high nine in the world, defeated Adrian Mannarino 6-3, 7-5.
Swiatek's unbeaten record ahead of the upcoming Australian Open was under threat after she lost the opening set to an aggressive Garcia, who was belligerent on return.
But Swiatek, a four-time Grand Slam champion, gradually gained control as she adjusted to the surface at the Ken Rosewall Arena with Poland having played all their previous matches at Perth's RAC Arena.
"Even though the surface is really similar, I would say I felt a little bit off with my rhythm," Swiatek said about the change of venue. "I'm happy that I came back and I didn't make so many mistakes as in the first set."
"I was making bad decisions and I needed to be more composed. After the break after the first set, I came back more focused, so I'm pretty proud of myself."
Swiatek ensured Poland improved on last year's semifinal finish when they fell to eventual champion United States in the inaugural United Cup.
Hurkacz had earlier outmuscled Mannarino and blasted 15 aces in his straight sets victory.
"I think definitely today was a real battle. Adrian was playing really, really tricky shots and it's really difficult to play against," Hurkacz said. "I think mentally I was able to stay in the present, stay positive before each point and I think I was also really resilient today."
In the later semifinal, former No. 1 Angelique Kerber saved two match points before prevailing over Australia's Ajla Tomljanovic 4-6, 6-2, 7-6(7) in two hours, 34 minutes.
In a gripping, see-saw of a contest, Kerber overcame a sluggish start and a partisan crowd to notch her first victory since returning from her 18-month maternity layoff.
"I think we both played at a really high level. It's so great to see her back after injury last year," Kerber said. "For me, it's the first singles win after coming back and it's really a great feeling."
Alex de Minaur leveled the tie after his red-hot form continued when he defeated No. 7 Zverev with a comeback 5-7, 6-3, 6-4 in two hours and 40 minutes.
It was No. 12 de Minaur's third straight victory over a top-10 opponent, having defeated Taylor Fritz and top-ranked Novak Djokovic during his purple patch.
In the best form of his career, the 24-year-old de Minaur will rise into the top 10 in the rankings on Monday, a feat not achieved by an Australian men's player since Lleyton Hewitt in July 2006.
"It's what I've worked so hard for. It's another milestone. But the job's not done," de Minaur said.