SaiPa needed overtime last time out against Assat to extend their winning run to five matches, and that record was surely going to be tested against a KooKoo side that had won nine of their last 10.
But the home side got off to the better start, as Teemu Kivihalme's powerplay goal in the sixth minute was all that separated the sides after the first period, though the tide appeared to be turning early in the second, when Emil Kuusla missed a penalty and Otto Paajanen levelled the scores.
An end-to-end next few minutes saw Maxime Fortier put SaiPa 2-1 up only for Joonas Oden to cancel it out soon after, before Miikka Salomaki gave the hosts the lead for the third time, scoring the fourth goal of the period with only 07:07 played.
However, KooKoo had no response before the 40-minute mark, and when Henri Nikkanen put two goals between the sides eight minutes into the third period, that was the platform SaiPa needed to win the game, as Salomaki added a second, before Juuso Heikkila scored shorthanded late on.
The 6-2 win lifts the Lappeenranta side to 97 points, one more than KooKoo, although the visitors have a game in hand. SaiPa trail Tappara by three and will play again before the league leaders take to the ice.
The new occupants of the final place in the top four are Ilves, who knocked Lukko out of the final automatic quarter-final place with a 4-3 win over one of their rivals for the position, KalPa.
Ilves did it the hard way, after the Kuopio side raced into a 2-0 lead through a pair of Konsta Kapanen goals, but four unanswered strikes in their favour, with John Nyberg notching two of his own in the middle period.
KalPa pulled one back in the final minutes, but it wasn't enough for the champions who sit in seventh place after three losses in a row, but just three points behind the Tampere club, who have put together as many successive victories.
Recent occupants of a top-four place, JYP, have overhauled KalPa and climbed back to sixth with a dominant third period in an 8-3 victory on the road at TPS Turku.
Two each for Alexander True and Lukas Wernblom played their part in the match still hanging in the balance after 40 minutes, with the visitors leading 4-3.
But they blew TPS away in the final period, as Pekka Jormakka and Otto Makinen grabbed two points each as JYP scored four in eight minutes to run out 8-3 winners. JYP improve their recent inconsistent record to three wins in seven, as Turku sit 11th after seeing their three-game winning run end.
Assat are clinging onto top four ambitions - they won 4-1 on what was their turn to beat bottom-of-the-table Vaasan Sport and stay eight points outside the coveted places. For Sport, it's just two points from their last 12 games.
Aarne Talvitie scored twice and Petteri Rimpinen kept a 26-save shutout as Kiekko-Espoo won 4-0 at home to IFK Helsinki. KE strengthen their ninth place in the standings, while HIFK remain in 12th with just two points between them and Hameenlinna outside the playoff places.