Despite going ahead twice, Peter Hutton’s men were forced to battle all the way against a dogged Mervue Utd side who drew level on two occasions.
Kevin McHugh put the Donegal side in front after just nine minutes and when Paul McVeigh added a second in the 30th minute, it looked like Harps were cruising.
But two goals from Alan Murphy in quick succession on either side of the break stunned Harps fans.
The Harps boss must have been thinking that defeat number three in as many outings may have been banging on the back door.
Paul McVeigh proved the Harps hero proving he too could snatch a brave as he netted what proved the winner in the 67th minute.
Ciaran Coll and Thomas McMonagle picked up yellow cards but Hutton will be pleased at grabbing full points.