Having been challengers for first place for a significant portion of the campaign, to miss out on the top four with four defeats in their final six regular season was disappointment enough for JYP, before failing to perform in the wildcard round.
But the night, and the series, belonged to Pelicans, who grabbed the only goal of the game in the 13th minute, as Brett Stapley stole the puck behind the JYP net and laid it back for the arriving Niklas Virtanen to power it into the net.
The Lahti side then sat deep to hold off wave after wave of JYP attacks, but the home side were failing to find a way past Patrik Bartosak, who made 29 saves and still needed some vital blocks from his defenders to hold onto the lead.
In comparison, Pelicans had just 12 shots on goal throughout the 60 minutes, and missed a rare scoring chance in the second period when Roni Karvinen failed to convert a penalty.
Discipline was the key to the away side's win, conceding just two two-minute powerplays across the match as they held on for the shutout victory and a place in the quarter-finals, where they will face either Tappara or KooKoo.
Following two overtime losses, Kiekko-Espoo had to win away at Assat to keep their season alive, and they did so in style, winning 5-2 to reduce the Aces' series lead to 2-1.
All seven goals came after the midpoint in the match, with Santeri Virtanen scoring his first of the series to put the visitors in front, only for John Stevens to concede a powerplay moments later, and Nestor Noiva levelled the game while his side had the extra player.
Just when the sides were looking inseparable again, KE took advantage of two powerplays of their own in the final three minutes of the second period to take control - Jan Mikael Jarvinen's trip was punished by Kasper Kulonummi, before Valtteri Viljanen's interference gave Lukas Svekjovsky the chance to make it 3-1.
With nine minutes left, Iikka Kangasniemi all but sealed the win for Kiekko, and though Feetu Knihti gave the Pori side hope, an empty-net goal from Ottoville Leppanen in the last minute finally ensured this series would go to game four.
The lowest-ranked side in the playoffs are one win away from the quarter-finals - Hameenlinna got the away win they needed to have a chance of upsetting Lukko, winning 3-1 in Rauma to go 2-1 up in the series.
The fifth seeds were far from convincing in their opening night win over the 12th-ranked side, before being shutout on their first trip to Hameenlinna. After 40 minutes tonight, they held a fragile lead after Topias Haapanen broke the deadlock six minutes into period two.
But the third period could go down as the best in HPK's season, after Cameron Wright equalised in the fourth minute, before Olli Korhonen reacted quickest to a loose puck behind the net and found Jesse Kiiskinen to turn the match on its head.
Lukko went for broke late on, but that only gave Kalle Kangas the chance in the final minute to score the empty-netter and wrap up the victory.
Liiga champions KalPa are on the brink of an early elimination, as after one 4-1 win apiece in Kuopio, IFK Helsinki and KalPa played out a rare goalless draw over 60 minutes in the capital, before the home side struck seven minutes into overtime to win it 1-0.
The win sees HIFK turn the series around following their defeat in game one, but it was beginning to look like it would never come, as the home side had 25 shots on goal to KalPa's 19 over three periods, while 11 powerplays were conceded in regulation.
The teams had another three fruitless efforts on goal each before HIFK finally found the net, when Aron Kiviharju's strike from the blue line was deflected in by Petr Kodytek, denying Talyn Boyko a playoff shutout and sealing one for Hugo Alnefelt.
IFK Helsinki, Hameenlinna and Assat all have the chance to join Pelicans in the quarter-finals when game four in the three ongoing series takes place tomorrow, 24th March.