Alexander Zverev saved two match points in a gruelling three-set win over Hubert Hurkacz to help Germany upset top seeds Poland and clinch a maiden United Cup title in Sydney on Sunday.

The world number seven kept the tie alive with his never-say-die 6-7 (3/7), 7-6 (8/6), 6-4 victory after top-ranked Iga Swiatek had swept past Angelique Kerber 6-3, 6-0.

Zverev returned to partner Laura Siegemund and seal the title with a 6-4, 5-7, 10-4 win over Swiatek and Hurkacz in the deciding mixed doubles.

"It was a matter of millimetres today for you guys (Poland) to be the champions," Zverev said at the presentation ceremony.

"To my team, it's been amazing and so much fun. I couldn't be happier."

Hurkacz and Zverev had not met since the 2021 ATP Finals, where the German was eventually crowned champion.

Both 26 years old and big servers, there were only small margins between them in the singles clash, with Hurkacz rising to the challenge in the first set tiebreak.

It went the distance again in the second set after the Pole saved two set points from Zverev at 5-6.

But this time, he lost his nerve in the tiebreak and blew two championship points as Zverev took it to a deciding set despite showing signs of fatigue.

With errors creeping in to Hurkacz's game, Zverev broke for a 4-3 lead in the third and, overcoming a bout of cramps, found a way to win.

"I was exhausted," said Zverev, with Germany's semi-final not finishing until 2.18am on Sunday.

"In the middle of the second set I was already exhausted and in the third set I was hanging on a lot of the time and somehow got the break," he added.

"Obviously mentally and physically, it was extremely difficult because playing three days in a row singles and mixed is tough."

Really proud 

Swiatek is in imperious touch heading into the Australian Open, dropping just one set throughout the mixed teams tournament to be on a 16-match win streak that began with her runs through Beijing and Cancun to end last season.

She was on another level to former world number one Kerber, who is on the comeback from an 18-month maternity layoff, winning the last nine games in a row.

"I feel like I just really improved during the pre-season and I'm happy that I played such solid matches here," said the 22-year-old.

"I'm really proud of myself that I could win all of my singles.

"I felt like she was really picking the right spots to play and she surprised me sometimes with her decision-making and choices," she added of Kerber.

"I knew she could play like that but I didn't have much time to get into the rhythm because sometimes she was really aiming these balls inside out.

"With the ball change, I felt like my game could be more dynamic and I could push Angelique more after 4-3 (in the first set)."

Kerber put early pressure on Swiatek, who saved two break points to hold for 3-2.

But the match turned when the Pole overpowered Kerber's serve to break for 5-3 and it was a demolition job from then on as Swiatek ran riot.

She will head to the Australian Open with wins over Caroline Garcia, Beatriz Haddad Maia, Sara Sorribes Tormo and Zheng Qinwen, along with Kerber.