Finland eliminated reigning champions Canada with a 2-1 Davis Cup last eight triumph, buoyed by fervent support as the finals began in Malaga on Tuesday.
Following their triumph in the Billie Jean King Cup earlier in November, Canada hoped to continue their success in the men's World Cup of tennis, but were ousted as Finland reached the semi-finals for the first time.
Canada's Milos Raonic eased to a 6-3, 7-5 win over Patrick Kaukovalta in the first singles rubber before Otto Virtanen kept Finland's hopes alive by beating Gabriel Diallo 6-4, 7-5.
Virtanen returned alongside Harri Heliovaara to triumph 7-5, 6-3 in the decisive doubles against Alexis Galarneau and Vasek Pospisil to delight a few thousand Finnish supporters on the Costa del Sol.
"We played really great doubles today ... we played really great together," said Virtanen.
"Why stop here, we have even more party on Friday," added Heliovaara.
Neither country had their top-ranked player available, with Canada's Felix Auger-Aliassime and Finland's Emil Ruusuvuori both hurt.
Raonic came flying out of the blocks with four aces to hold to love in the first game against Kaukovalta and racked up 18 in total in his straight sets triumph.
The former world number three made his competitive comeback in June after nearly two years away because of injuries but his high-power serve remains as lethal as ever.
Despite a splash of Canadian red in the stands at the Martin Carpena arena being outnumbered by those in blue and white, the Canadian held his nerve in his first Davis Cup match since 2018.
After breaking for a 5-3 lead in the first set and serving it out, dropping just one point on serve in the process, Raonic lost only two more in the second set of his convincing victory.
"I have definitely never played against anyone with that kind of serve," said Kaukovalta.
"I had no read for it at any point of the match."
However Virtanen, who played a key role in Finland's progress to the Davis Cup finals, gave Finland's support plenty to cheer about.
"In front of these fans it just makes me play better every time," said Virtanen, showing power and fine reflexes to dispatch Diallo with a break in both sets, forcing the decisive doubles.
The Finnish duo got the better of 2014 Wimbledon doubles champion Pospisil and his partner Galarneau, breaking at the second time of asking to take the first set 7-5.
They broke again for a 5-3 lead in the second set and served it out, Virtanen clinching victory with an ace.
Finland will face Australia or the Czech Republic in Friday's first semi-final.