Looking to challenge the top four, a derby when their neighbours are so out of sorts looked to be good timing for Ilves.
But that wasn't holding true when Eetu Tuulola gave Tappara an eighth-minute lead, only for a tripping call against the same player allowed Carl Klingberg to level matters on the powerplay before the first period was up.
However, the Lynx failed to kick on despite another pair of powerplays before the mid-point, and Tappara punished them with goals from Kristian Tanus and Otto Rauhala to make it 3-1 after 40 minutes.
A plethora of powerplays in the third period gave both sides the chance to change the game, but it wasn't until Ilves pulling the goaltender backfired that the result was secured with 90 seconds to play, as Emil Sylvergard struck the puck into the empty net to round off the 4-1 win.
It's two losses in three now for Ilves, albeit against the current top two, while Tappara register their first win of the month.
The Battle Axe remain four points clear of KooKoo, who saw seven different players score and only two players register two points in a 7-3 win over Hameenlinna that was a real team effort in attack. It's successive wins for KooKoo, who go second, while successive losses keep the visitors in 13th place.
In third on goal difference, Lukko have now won six on the bounce as Daniel Salonen made 27 saves to keep a shutout in their 4-0 win away at IFK Helsinki, who have now failed to score in two games in a row.
On a five-match winning run and still just a point further back are KalPa, who came from behind to record a 5-2 win on the road at Karpat to go fourth, while the Oulu side slipped back to 15th place following a third defeat in succession.
The big losers tonight arguably are SaiPa, despite not playing - they dropped from second to fifth, although they are just one point behind KooKoo.
However, the biggest losers who actually played were JYP, who shipped nine goals away at Pelicans to now sit three points shy of the top four in sixth place.
Things began brightly for the visitors, as Pekka Jormakka gave them the lead in the second minute, but they had no answer to two Einari Luhanka goals, plus strikes from Roni Karvinen, Eelis Teutari and Miro Vaananen all before the first period was over.
Elias Huttu pulled one back approaching the halfway mark, only for Aidan Dudas to restore the four-goal cushion late in the second period.
But the relentless Pelicans weren't done there, as Kim Nieminen scored two in the space of five minutes to extend the advantage further, before Joona Kumpula rounded off the scoring with a powerplay goal with two minutes left, making the final score a resounding 9-2 to the Lahti side.
It's just a second win in five for the hosts, for whom Dudas led the way with four points. They sit 11th with a six-point gap from those outside the Playoff places. For JYP, it's now three losses in their last four.
Jukurit threw away a 2-0 lead, only two win the penalty shootout by the same scoreline to beat Kiekko-Espoo, 3-2. That ends a seven-match losing run for the Mikkeli men, while KE have been beaten for the first time since 24th January.
The gap between Jukurit and the Playoff places has extended to eight points, as TPS Turku solidified their 12th place with a 3-1 win over Vaasan Sport, who remain cut adrift at the bottom.