The victory is all the more impressive given that conceding the winning goal in the 130th minute meant the 2-0 series lead they had established had been wiped out, and though Tappara had just as little time to recover, the first seeds had all the momentum and a home game to look forward to.
The first period was goalless, but ended with a key incident that allowed Tappara to take the lead in their bid to make home advantage count. Having survived an early powerplay for tripping by Joseph Berger, KooKoo then lost Vilmos Gallo for high-sticking in the final minute.
That meant Tappara began the second period with an extra man, and this time they wouldn't be stopped on the powerplay, as Julius Mattila squared to Joachim Blichfeld, whose powerful shot gave Eetu Randelin no chance.
But back to full strength, KooKoo found the form that saw them win the opening two games of the series, scoring twice in under four minutes. Just past the midpoint of the match, Kim Nousiainen played a quick one-two with Samuel Valkeejarvi and fired through the crowd to level the scores.
Then, the Kouvola side turned the match on its head when Ossi-Petteri Jaakola's wonderful reverse pass at the blue line found Miska Siikonen, who weaved his way through the defence and his shot had just enough on it to beat Christian Heljanko.
In the third period, the Tampere side threw everything at the visitors, but when the KooKoo defence weren't making one of nine blocks, Randelin was putting in a match-winning performance, making 13 saves in the final 20 minutes to take his tally for the match to 30.
That allowed KooKoo to hold out for the 2-1 win, their second in Tampere of the series, and now they take the series lead to Kouvola for game six on Monday 11th May, knowing victory will see them become champions of Finland for the first time.