Alexander Zverev led Germany into the semi-finals of the United Cup on January 5 after winning his singles rubber against Greece's Stefanos Tsitsipas before partnering Laura Siegemund in the mixed doubles to clinch the decider.
World number eight Maria Sakkari had given Greece a 1-0 lead with a 6-0 6-3 win over three-time Grand Slam champion Angelique Kerber, before Zverev defeated Tsitsipas 6-4 6-4.
With the team score tied at 1-1, Zverev returned to the court soon after to play the mixed doubles decider, where the Greek pair of Petros Tsitsipas and Sakkari were beaten 6-3 6-3.
"I was taking a back seat (playing) with Laura. I think we deserve to be in the semi-finals," Zverev said.
Zverev was aggressive in the singles, doing damage with his first serve and although Australian Open runner-up Tsitsipas hit 16 winners, his 24 unforced errors allowed Zverev to cruise past the world number six.
Zverev, who fell in the second round of last year's Australian Open following his comeback from an ankle injury, is hoping to progress further in the Grand Slam this year.
"Being healthy is the biggest thing for any athlete, the mindset this year is different," Zverev said.
"I hope that I can stay in Australia a bit longer maybe a bit more successful, I've already won more matches this year than I did last year so I'm happy."
Earlier, Sakkari comfortably beat Kerber, who is playing her first tournament in 18 months after a maternity break.
Sakkari got off to a flying start, speeding through the first nine games of the match to take the first set and rack up a 3-0 lead in the second before Kerber was finally able to hold serve.
The hold appeared to spark Kerber into action as she broke to bring the second set back on serve at 3-2, but her brief resurgence was quickly squashed by Sakkari, who claimed her third straight singles win of the tournament.
"I was pretty clinical in the first set and through 3-0 in the second, I was very solid from the baseline doing what I had to do," Sakkari said.
"I knew Angie was going to find a way to come back and that she wasn't going to give up. After the first set I said there was no way the match will go super easy."
Poland take on France in the other semi-final. (Reporting by Shifa Jahan and Aadi Nair Editing by Toby Davis)
