Finn Harps moved to the summit of the Eircom League Division One table for the first time this season as they overcame Cobh Ramblers in their top of the table clash at Finn Park.
The Donegal side are now a point clear with just six games to go thanks to a dramatic 84th minute winning strike from Conor Gethins.
Cobh, who went into the game on the back of a 27 game unbeaten run in the league, shaded a first half in which both sides showed plenty of endeavour but chances were at a premium.
Harps, with eight wins in their last nine outings, were determined to extract revenge for their 2-0 defeat at the hands of the southerners at the same venue earlier in the season.
And they were boosted before the kick-off by the news that first choice goalkeeper James Gallagher - who had a hip injury - was deemed fit to play.
Harps had a real let-off after just seven minutes when goalkeeper James Gallagher took down the advancing Kieran O'Reilly following a poor back pass.
But the Harps number one redeemed himself by saving Alan Carey's penalty.
And the visitors, who forced three early corners, gave Harps another scare shortly afterwards when O'Reilly had a shot blocked in the box and Kevin Murray's follow-up shot was deflected wide with the home defence fully stretched.
The Donegal side's first chance of note came on 20 minutes when Conor Gethins surged into the box only to fire weakly at James McCarthy.
And the 'keeper was in action again seven minutes later as he rushed out to thwart Gethins once more.
With a crowd of almost 3,000 urging them on, Harps attempted to step up a gear in the second half, but defences remained on top.
Mark Brolly blazed the ball over the bar for Harps on 54 minutes but both sides were struggling to find the creativity needed to unlock the stubborn defences.
However, on the hour, Harps went agonisingly close to breaking the deadlock. Stephen Parkhouse played a delightful ball over the Cobh defence for Shaun McGowan to run onto but his lob over McCarthy hit the post.
This really lifted Harps with Michael Funston and Parkhouse (twice) both going close as the game finally began to open up.
But sides looked nervous at times, knowing that a defeat could jeopardise their league hopes, and the closing stages proved to be very tense.
Harps threw on substitutes Declan Divin and Chris Breen to a bid to bag the full points and a late spell of pressure paid off as Gethins pounced to rifle the ball into the top corner in the 84th minute
Cobh had John Kearney sent off in the final minute for dissent.
Finn Harps: Gallagher, Asokuh, Minnock, Boyle, Holmes, Shields, Funston, McGowan, Parkhouse, Gethins, Brolly. Sub: Divin for Brolly (78 mins), Breen for Funston (82 mins), McLaughlin for Shields (90 mins).
Cobh Ramblers: McCarthy, Carey, Meade, Murray, Guthrie, Coleman, Cummins, Kearney, O'Reilly, .O'Shea, Cambridge. Subs: O'Neill for O'Shea and Meade for Cambridge (both 88 mins).
Referee: Mr. R. Winters (Dublin)