The match in Kuopio pitted together the teams with the two current longest winning streaks, but by the fifth minute it was only KalPa's that was set to continue, after Andreas Okany gave them the lead.
But Hameenlinna's four-match winning run - and five wins in six matches - was their best form all season, and they weren't about to give it up lightly. A key man in their recent form, Cameron Wright, drew them level with four minutes of the opening period to play.
The visitors held out for almost exactly 20 minutes, as following a stick-holding call against Miska Kukkonen, Juuso Maenpaa put KalPa ahead again with four minutes of the second period to go.
In the final period, Hameenlinna went for broke in search of an equaliser, but they lost possession having taken out the goaltender, allowing Okany to score his second of the match and seal the 3-1 win with an empty-netter in the final minute.
KalPa are now fifth, two points behind Lukko, having now played the same number of games.
One defeat was enough for Hameenlinna to lose their position in the Playoff places; they were knocked back to 13th by Jukurit, who claimed a 6-2 win at home to Vaasan Sport to go 12th.
Following a goal each in the first 20 minutes, Jukurit all but won the match with three goals in the first 9:09 of the second period, rounded off by a second of the game for Aleks Haatanen.
Ilvari Heikkinen completed a brace of his own to get it back to 4-2, but in the final five minutes of the match, two more goals for the hosts secured a comfortable win in the end. It's a first win in three for the Mikkeli side, while bottom-of-the-table Sport have lost two in a row.
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