Harps will travel to take on St Patrick’s Athletic while Derry have been drawn away to Shamrock Rovers.
Both matches will be played on Sunday, 5 October, kick off times to be confirmed.
As a result, league fixtures involving City and Harps for that weekend have been changed.
Finn Harps’ First Division clash away to Wexford Youths , originally scheduled for Friday week, October 3, has been rescheduled for Tuesday next at Ferrycarrig Park with a kick-off time of 8.00pm.
City’s Premier Division clash with Bray Wanderers, which was originally fixed for Friday week, 3 October, has also been rescheduled for Tuesday next, 30 September at the Carlisle Grounds with a kick-off time of 7.45pm.