Since falling to an overtime defeat in game one, KooKoo have been dominant against Pelicans, and secured the series with a 4-1 victory, their fourth success in a row by at least a three-goal margin.
Pelicans weren't helped by an early interference call against Johannes Johannesen, and a swift attack exposed their defensive frailties on the resulting powerplay, as Jimi Suomi applied a neat finish to open the scoring in the seventh minute.
Six minutes later, KooKoo looked to be cruising to another comfortable win, when Vilmos Gallo passed back to Ville Puhakka just inside the blue line, and his shot flew through the crowd and in for 2-0.
But the home side failed to kill the game off in a goalless second period, and that was coming back to bite early in the third, when Niklas Virtanen's speculative attempt to send the puck in front evaded everyone and hit the net.
However, the Kouvola side were not about to throw this one away, and after Puhakka saw a second goal disallowed, Joonas Oden stole the puck at centre ice, found Gallo with a pass, and when his shot struck the pipes, Marcus Davidsson was on hand to tuck away the rebound.
The Lahti side's attempts to keep their season alive fell apart in the final minute, when Oden again won possession, this time in his own zone, and sent the puck sliding down the ice and into the empty net for 4-1 on the night, and 4-1 in the series.
The records will show that Tappara had an equally comfortable 4-1 series win in the quarter-finals against Hameenlinna, but the 1-0 win in game five was the fourth of the tie to be settled by a one-goal margin, showing just how closely the 12th seeds pushed the regular season champions.
It's hard to argue the Battle Axe didn't deserve this victory, with just over double the number of shots on goal HPK managed. The only one that mattered in the end, came four minutes into period two.
On an attack that started behind the Tappara goal, Juuso Nykanen cut in from the left wing and attempted to tuck the puck past the goaltender, which caused a huge melee in front of the HPK goal, at some point in which, Emil Sylvegard poked it over the goal line.
The officials checked for goaltender interference and whether the puck had indeed gone in, among other potential fouls, before eventually deciding the goal stood.
HPK had two powerplay chances later in the second period, which they failed to make use of, then their potential fightback in the third was hampered three powerplays conceded, and though their defence held firm, they failed to find a way past Christian Heljanko, who made 16 saves in his shutout.
With the other two quarter-finals - SaiPa vs Assat and Ilves vs KalPa - locked together at 2-2, Tappara and KooKoo must wait until at least 11th April to discover their semi-final opponents.