Damien Duff felt his Shelbourne side deserved at least a draw at Finn Park, only for Barry McNamee to strike the winner in the 89th minute.
Neither goalkeeper had a save to make over the course of the match and it looked to be headed towards a scoreless draw when McNamee, wearing the captain's armband in the absence of of Dave Webster through injury, struck a dramatic winner with time almost up.
"If anything we looked the dangerous team throughout," the Shelbourne manager said. "I don't think Harps deserved to win the game. It wasn't meant to be. We're disappointed second phase of a corner but the lads are good but we will have to pick them up."
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