Events at Fir Park saw St Mirren, Dunfermline's relegation rivals, grab an unlikely comeback victory against Motherwell. The late drama in Inverness led to tears as the stunned visiting support and players took in the reality of the afternoon.
It all seemed to be going so well for Stephen Kenny's side as they began the brighter of the two sides. However, the first chance fell to the Highlanders when Ross Tokely crossed for Graham Bayne but his header was held by keeper Dorus de Vries.
The Pars came back into the game and Scott Muirhead tried his luck from distance but keeper Mike Fraser was equal to the shot.
The visitors continued to attack and Jim McIntyre flashed a shot just wide after 12 minutes. The hosts came forward with more purpose moments later and Craig Dargo's angled drive was caught by de Vries.
At the same end Bayne should have done better when Richard Hart found him but he shot over from 20 yards.
The Pars took the lead with a wonderful goal eight minutes before the break. Tom McManus played the ball through for McIntyre and he volleyed fantastically into the roof of the net to spark wild celebrations in the South Stand.
Inverness could have levelled matters seconds before the half-time whistle when Hart was set up by Dargo but the midfielder's fierce shot was parried by de Vries.
With Motherwell leading St Mirren, the afternoon appeared to be going well for Dunfermline. The Fifers almost went 2-0 ahead just after the break in bizarre fashion when keeper Fraser had to tip over a wayward touch by his own defender Darren Dods.
Dunfermline's McManus then almost made it two for the Pars when he stole into the penalty box but Fraser got down well to save.
Then, on 77 minutes, Inverness grabbed an equalsier in sensational style. Canadian Richard Hastings saw his free-kick wriggle out of the grasp of de Vries and skid into the net causing red faces for the visiting keeper. It was later revealed this was Hastings' first goal in 11 years for the club.
Inverness almost edged in front when Bayne headed wide. Dunfermline also found extra energy for a final push and McManus headed straight at Fraser before Gary Mason squandered a chance from just eight yards.
The killer moment came when sub Rory McAllister watched his deflected shot swerve into the net for a late winner that had devastating consequences for Dunfermline.