A 1-0 defeat to Glentoran on Tuesday night means Larne will now take part in next week’s play-off for the last remaining Uefa Conference League spot.
Conor McMenamin struck two minutes into the second half to move Glentoran four points clear in third place, with one league left to play.
It was a tight encounter throughout, with Glentoran managing to edge it with the goal they needed to claim European qualification for another year.
The first effort of the night was a speculative one from Ronan Hale, on six minutes.
Mark Randall pressed the ball high up the pitch on the right flank, and slipped the ball to Larne’s top scorer, but Hale’s effort drifted well wide, despite Dayle Coleing being well off his line.
Larne were comfortable at this point, but it took them another 20 minutes to create a chance of note.
With 24 minutes on the clock, some neat footwork from David McDaid saw him slip the ball right to Mark Randall, and the midfielder has a go from outside the angle of the box but this time it was a comfortable stop for Coleing.
Glentoran grew into the game as he half wore on, but a couple of Dale Gorman free-kicks was as much as they had to show for in front of goal.
Mick McDermott’s men made the perfect start to the second half however, when they broke the deadlock on 47 minutes.
Good work from Jay Donnelly saw him get to the byline on the left flank, and his cross was flicked to the back post where McMenamin was on hand to flick home.
With their tails up, Glentoran had an opportunity to really stamp their authority on the contest two minutes later.
This time Robbie McDaid made the opportunity when he picked up the ball on the left side of the box before controlling well, stepping inside but blazing well over.
Soon after this, Larne boss Tiernan Lynch went for broke in a game they knew they had to win, throwing on forward Johnny McMurray for midfielder Mark Randall.
This saw them take the game to their visitors, but still struggled to create many meaningful opportunities.
With 20 minutes to go, Davy McDaid tried his luck, after driving at the Glentoran defence but fired wide of Coleing’s righthand post.
There was controversy with 13 minutes left when the Glens thought they should have had a penalty.
Jay Donnelly raced clear of the Larne defence and skipped past the Conor Mitchell, who had raced out of area and rolled the ball towards an unguarded net. Home skipper Jeff Hughes blocked the ball with the visitors making strong appeals for handball.
Referee Steven Gregg waved away the appeals, with assistant boss Paul Millar getting sent off for his protests and Hughes having to be withdraw with what looked like a hamstring injury.
Larne went for broke in the closing stages, with sub Marty Donnelly seeing a free-kick deflected just over, with Albert Watson and Josh Robinson heading just wide from corners.
For Larne that was as close as they came to a leveller, and they now know they’ll be in a play-offs in a bid to claim the last European place next week.
Larne: C Mitchell, Watson, Robinson, Herron, Sule, Randall (McMurray ’57), Hale, McDaid (Donnelly ’72), Cosgrove, Hughes (Lynch ’77), Jarvis
Unused subs: Kelly, Scott, A Mitchell, Wade Slater
Glentoran: Coleing, Kane, McCullough, Gorman (Crowe ’89) Bigiramana, Gallagher, McClean, McMenamin (Clucas ’78), Marshall, J Donnelly (Mitchell ’87)
Unused subs: Morris, O’Connor, Cowan, Stewart
Referee: Steven Gregg