Livingston boss David Martindale admitted a slump at the wrong time of the campaign ultimately put paid to their top six hopes.
A 2-0 away loss at Dundee United saw them end up on the wrong side of the split for the second straight campaign - despite looking near certainties to book their place a couple of months ago.
A run of just 10 points from their last 12 games saw them miss out in agonising fashion as a 25-yard strike from Jamie McGrath was added to by a late Steven Fletcher goal after Cristian Montano had been caught in possession.
The Lions headed into the clash knowing they had to win to have any chance - and that had to be coupled with Kilmarnock beating St Mirren in Paisley or Hibs being held at McDiarmid Park by St Johnstone.
But the visitors produced an insipid display that belied the opportunity being presented to them with a lacklustre display.
Even knowing that both results were in their favour failed to spur much of a reaction as the season petered out.
A dejected Martindale said: “Disappointment is the overriding emotion.
“I think we could have played for 180 minutes and it would have been difficult to score. Give Dundee United credit, I thought they defended extremely well.
“For me from matchday 21 I think we threw away top six. I think we had one foot in the door at certain points in the season but we’ve had a poor run of form in those 12 fixtures.
“This was a missed opportunity but we didn’t throw it away today. We had plenty of other opportunities.”
He added: “As a group we’ve got five games left and it’s a special group of players. I’m going to lose some of them in the summer.
“There’s boys on their knees and in tears. There’s huge disappointment and I’ll take accountability for that.”
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