Ryan Brennan headed home the only goal of the game as Shelbourne took the points from their visit to Finn Park on Tuesday night.
It means the Tolka Park outfit climb to fourth in the Premier Division table while Harps have now dropped into the bottom three.
With another big game to come on Friday night away to St. Patrick's Athletic, Harps keeper Mark Anthony McGinley insists the team need to find improvement for what promises to be another difficult test.
He spoke with Diarmaid Doherty after Tuesday night's 1-0 defeat to 10-man Shels.
If you have a story or want to send a photo or video to us please contact the Donegal Live editorial team any time. To contact Donegal Democrat and Donegal People's Press, email email@example.com To contact Donegal Post, email firstname.lastname@example.org To contact Inish Times, email email@example.com.
Subscribe or register today to discover more from DonegalLive.ie
Buy the e-paper of the Donegal Democrat, Donegal People's Press, Donegal Post and Inish Times here for instant access to Donegal's premier news titles.
Keep up with the latest news from Donegal with our daily newsletter featuring the most important stories of the day delivered to your inbox every evening at 5pm.