Larne booked their place in the European play-offs decider thanks to a stoppage time winner over Glenavon at Inver Park.
Glenavon raced into the lead with just under five minutes on the clock courtesy of Daniel Purkis' header from a few yards out after Larne had failed to clear a corner.
But, just three minutes after that, the sides were level again after David McDaid popped up to equalise into the bottom corner after Ronan Hale's initial effort from Martin Donnelly's corner was cleared off the line.
McDaid might have edged Larne in front not long after that but was thwarted by a goalline clearance while the same player was played through into a dangerous position a little later only to be ruled out offside.
And McDaid was denied by the offside rule again after around half-an-hour when he did find the net for a second time from a Mark Randall through ball.
Chances proved a little more difficult to come by after the break but Ronan Hale did come close when he found himself in a good position but could only skew the ball wide.
For Glenavon Peter Campbell proved to be a threat with a fiercely struck left-foot shot from distance which whistled just past the left upright.
But, in the end, it was to be Larne's night.
Albert Watson might have snatched victory late on but could only flash a header wide from a corner to the near post before, deep into stoppage time, Donnelly grabbed what proved to be the winner with a right-foot curling finish beyond Craig Hyland after Conor McKendry had provided the decisive pass.
Larne: C. Mitchell, Watson, Robinson, Herron, Sule, Randall, Hale, McDaid, Donnelly, Cosgrove, Jarvis subs Scott, Lynch, A. Mitchell, McKendry, D'Sena. McMurray, Lusty
Glenavon: Hyland, A. Doyle, Purkis, Campbell, Hall, Snoddy, Fitzpatrick, Douglas, Garrett, Ward, McNulty subs Coates, Birney, Byrne, McCloskey, O'Mahony, Norton, J. Doyle