Following a narrow loss to the climbing KalPa last time out, JYP's own spot in the top four was under threat, but any suggestions that they would provide the welcome relief Lukko were looking for were dispelled in just over 13 minutes of their clash.
It took Sami Vatanen only 24 seconds to break the deadlock for the home side, and JYP thought they were 2-0 up after just 44 seconds, but Tobias Winberg's goal was disallowed following a successful coach's challenge.
The second goal JYP had been threatening finally came midway through the period, courtesy of Alexander True, then the Rauma side's night got worse when Antoine Morand was called for holding and Juuso Puustinen scored on the resulting powerplay.
The visitors showed plenty of determination to reduce the deficit in the second period, but not only were they struggling to find a way past Oskari Setanen, they went further behind when Valtteri Ojantakanen punished them with another powerplay goal in the 17th minute.
Jakob Stenqvist finally got Lukko on the board with a minute left in the period, but after 19 shots on goal in the second period alone, it was looking like too little too late for the away side.
That was true in the end, but only after Lukko fell just short of a remarkable comeback, as Morand scored with just under four minutes to play, then Antti Saarela made it 4-3 in the final minute, but that was how it finished, taking JYP within three points of second-placed SaiPa.
KalPa were well on course to replace Lukko in the top four and secure a seventh-consecutive win when they went 2-0 up at TPS Turku early in period three, only for Tarmo Reunanen and Aleksi Saarela to level things up for the hosts to send the match to overtime.
And in the extra period, it took less than a minute for TPS to complete the turnaround when Lukas Wernblom fired home the winner to give the hosts a first win in three, as the Kuopio not only fail to go fourth, but drop a place to sixth.
That's because Ilves have climbed above Lukko and KalPa into fourth with a 5-2 win at home to struggling Vaasan Sport. Matias Mantykivi scored twice as the Tampere side earned a third win in four, while Sport now have zero wins in four and stay 12 points below Karpat.
League leaders Tappara threw away a 2-0 lead at Jukurit, before Aleksi Matinmikko scored the winner to make it 3-2 with one second of regulation time remaining. That late drama extends their advantage at the top to seven points, while Jukurit remain in 12th on goal difference.