Naomh Conaill have progressed to the Ulster Club Football semi-finals after a 1-11 to 0-11 win over Cavan champions Castlerahan at Kingspan Breffni.
The Donegal champions led by seven midway through the second half but Castlerahan fought back to trim the margin to only two in injury-time.
However, Dermott Molloy's steadying point sealed Naomh Conaill's success.
Brendan McDyer, Kieran Gallagher, Ciaran Thompson and McGuinness hit the first four scores of the game for Naomh Conaill before Cormac Daly opened Castlerahan's account in the 18th minute.
A Ciaran Thompson goal put the Glenties side six clear but points from Stephen Cooney, Karl Cosgrove and Daly have left only a kick of the ball between the sides at half-time.
Castlerahan could have been even closer at that stage as Naomh Conaill keeper Stephen McGrath saved an Enda Flanagan goal chance just before the break.