Alexander Zverev shrugged off a tight loss to Novak Djokovic to end Serbia's ATP Cup title defence with victory in the doubles as Germany advanced to the semi-finals of the team-based event in Melbourne on Friday.
Germany will meet Russia in the last four, with Spain to take on Italy.
Zverev, beaten 6-7 (3), 6-2, 7-5 in a high-quality match by world number one Djokovic earlier on Friday, stepped up to partner Jan-Lennard Struff to a rousing 7-6 (4), 5-7 (10-7) victory over Djokovic and Nikola Cacic on Rod Laver Arena.
"I was quite frustrated with how the singles ended in a way," Zverev said on court.
"Still got to give myself some time.
"We played well, both of us," he added of his doubles match with Struff, who beat Dusan Lajovic 3-6, 6-3, 6-4 in the opening singles rubber.
Djokovic's 11-match winning streak in the team tournament was broken, and he will have no more match practice before his Australian Open title defence.
"I am upset that we lost, that's all I can say, I'm not thinking about the Australian Open or anything else," said Djokovic.
"It’s unfortunate we lost the tie. That's what this competition is all about. It's about the team, not about winning one match, (a) singles match. We'll try another time."
A year after crashing out of the inaugural ATP Cup with a huge tally of double-faults, Zverev's serving demons returned under pressure against Djokovic in the singles and again in the doubles on Friday.
He was broken at 5-5 in the second set of the doubles after two double-faults but nailed his serves when Germany grabbed match points in the super tiebreak.
Djokovic consoled himself that he had an excellent warmup against Zverev in the singles.
"I thought it was a great match. I thought we both played well ... He definitely had a big serving match. It was so difficult to play against him today," he said.
With Rafael Nadal still sidelined with a back problem, Pablo Carrena Busta guided a depleted Spain into the last four by claiming a 6-3, 6-4 win against Greece's Michail Pervolarakis at John Cain Arena.
Though eliminated, Greece ended up winning the tie 2-1, with Stefanos Tsitsipas easing past Roberto Bautista Agut 7-5, 7-5.
Spain retired after losing the opening game of the doubles, handing Greece the win.
In a dead rubber between Austria and France in the evening, world number three Dominic Thiem's hopes of getting some match practice were cut short when his French opponent, Benoit Paire, retired while trailing 6-1.