Four defeats in their previous five had seen Assat's position atop the table disintegrate, and while Jukurit were not in sparkling form either, tonight's visitors had only lost narrowly to some of Liiga's in-form sides and were expected to provide a stern test.
That proved to be the case, as neither side managed to find the net in the first 30 minutes, and with three powerplays to Assat's one in that time, the Mikkeli side were left ruing missed opportunities when Aleksi Anttalainen struck for the Aces with three minutes of period two remaining.
The home side came out for the final period with their tails up, and two goals in the opening seven minutes - from Johan Olofsson and Valtteri Lipiainen - put the result beyond doubt, before Lassi Vanhatalo rounded off the 4-0 victory late on.
Jan Bednar made 15 saves to complete his shutout, with just four required in the final 20 minutes, as Jukurit seldom looked like making a comeback. Tappara will have the chance to re-open a five-point lead tomorrow when they meet IFK Helsinki away from home.
JYP also fell off the pace in recent weeks, but have climbed back into third position, above KooKoo, with their second victory in as many matches, although a 2-1 win secured in a penalty shootout away at TPS Turku will hardly strike fear into those sides around them.
Jere Lassila broke the deadlock for the visitors inside five minutes, and that lead lasted until the eighth minute of the second period when Sisu Yliniemi responded with a powerplay strike for TPS.
No goals in the third period or in overtime meant the match would be settled in a shooutout, in which Leevi Tukiainen stepped up to be the JYP hero, scoring a game-winner to take the shootout 3-2.
JYP are now a point clear of KooKoo, who meet KalPa tomorrow, while TPS are ninth, a point and a place ahead of Jukurit, following successive losses.