FINN HARPS clinched a first ever league win at Brandywell as the league's top scorer Adam Foley netted an 89th minute strike to end Derry City s four game unbeaten run.
The Candy Stripes had taken the lead in the first North West derby of the season against the run of play when James Akintunde's curling strike found the corner of the net after 17 minutes.
Will Seymore's spectacular strike from 35 yards crashed off the woodwork while Will Patching's free-kick bounced off the top of the crossbar at the start of the second half.
Karl O'Sullivan's strike deflected off Cameron McJannet to get Harps on level terms on 55 minutes and just as it looked to be heading for a third consecutive draw between the teams, Foley latched onto Barry McNamee'sneat pass and fired into the net.
City skipper Eoin Toal headed a close range strike off the post with the last action of the match but the home side fell to a fifth defeat of the campaign.
After two wins on the bounce under Ruaidhri Higgins there were high hopes of a first home win since October 23rd but the home side were left licking their wounds.
Higgins made two changes from the team which won at Dalymount on Friday night with David Parkhouse and Jack Malone making way for Joe Thomson and Brendan Barr.
The Ballybofey men put their hosts under sustained early pressure and former City skipper Barry McNamee came close to opening the scoring less than two minutes into the game.
Foley linked up neatly with O'Sullivan on the right wing and the latter's first time cross was met on the half volley by McNamee who steered his effort just wide of the far post.
Harps striker Tunde Owalabi chased a long ball over the top and when Eoin Toal hesitated, the Belgian took advantage but his shot was blocked down superby by the advancing Nathan Gartside.
The Donegal men were made to rue those early missed chances as Derry took the lead on 17 minutes with their first meaningful attack of the match.
Akintude received the ball wide on the left side of the penalty from Patching before travelling inside and rifling a stunning curling strike into the far corner of the net - the Londoner's first of the season!
Patching then tried his luck with a searching strike from 25 yards but Mark Anthony McGinley did well to palm it away at full stretch on 22 minutes.
A short McNamee corner found Mark Russell who peeled off the shoulder of his marker and fired a left footed effort narrowly over the bar on 24 minutes as Harps continued to assert pressure.
There were suspicions of offside when Owolabi was played in behind the Derry defence on 32 minutes but it didn't matter as the striker's low shot was saved by Gartside.
Will Seymore rattled the top of the crossbar with a spectacular strike from 35 yards on the stroke of half-time as Derry went into the interval with a narrow lead.
Derry struck the woodwork immediately after the restart as Patching's inswinging set-piece bounced off the top of the crossbar.
Harps were back on level terms 10 minutes into the second half when Derry failed to clear after David Webster's point blank header was parried clear by Gartside.
O'Sullivan picked up the scraps and his strike was deflected into the net off the outstretched leg of McJannet.
City's top scorer, McJannet tested the keeper's reflexes at the other end with a low strike from 25 yards but McGinley turned it wide for a corner.
Danny Lafferty's long range strike arrowed wide of the post on 78 minutes and the left-back volleyed over the bar moments later as Derry pushed for a late winner.
The Candy Stripes came so close to clinching maximum points with five minutes on the clock as Fitzgerald's neat pass found the run of substitute Malone but the midfielder's first time strike hit the foot of the post.
It was Harps who snatched the win at the death as McNamee found Foley with a lovely pass inside the penalty area and the striker fired clinically into the net.
City skipper Toal headed off the post from Akintunde's cross with what was the final action of the game as the Ballybofey men moved six points ahead of their North West rivals as Derry slipped to eighth.
Derry City: N. Gartside; R. Boyce,E. Toal, C. McJannet, D. Lafferty; W. Fitzgerald, C. Harkin (P. Ferry 89), J. Thomson (J. Malone 69) B. Barr (D. Parkhouse 55); W. Patching; J. Akintunde; Subs Not Used - J. Lemoignan, M. Glynn, C. McLaughlin, D. Lupano, M. McFadden, M. McChrystal.
Finn Harps: M. McGinley; K. Sadiki, D. Webster (E. Boyle 66), W. Seymore, S. Folan; K. O'Sullivan, B. McNamee (T. McNamee 89), M. Coyle, M. Russell, T. Owolabi (J. Browne 82); A. Foley; Subs Not Used - M Timlin, N. McGinley, R. Rainey, S. Doherty, J. Bradley-Walsh, L. McNicholas.
Referee: Paul McLaughlin (Monaghan).