Ollie Horgan made ten changes to his side that beat Bray 1-0 in the League on Friday night last as they faced Galway Utd in the League Cup this evening.
But after a 0-0 stalemate at Eamonn Deacy Park, Harps finally lost out on penalties.
And ironically it was former Harps striker Ruairi Keating who as the Galway hero as he finished the decisive penalty.
Keating should have scored during normal play but hit the crossbar.
Ciaran Gallagher came to the rescue of Harps on a number of occasions but neither sid could break the deadlock.
In the shoot out Ryan Curran and Ethan Boyle missed their spot-kicks for Harps while Tony McNamee and Matthew Crossan scored as Galway scored four out of five of their penalties.