Ryan Henderson's early header was enough to give Donegal Celtic victory over Championship side Institute in Tuesday's Irish Cup fifth round replay.
Attacking midfielder Henderson scored in the 10th minute after Kevin Keegan's throw-in from the right had been touched on by Paul McVeigh.
Henderson had a chance to score again just two minutes later but scuffed his shot wide.
Institute's Stephen Parkhouse was sent-off near the end for an elbow offence.
Donegal Celtic play Cliftonville in the last 16 on 11 February.
Institute had their chances in the first half and central defender Paddy McLaughlin headed over from Declan McKeever's cross.
For DC, Darren Murray headed off target after Johnny Harkness had played a ball in from the left.
Sean Hawkins was in charge of the Belfast team in the wake of Paddy Kelly's resignation as manager on Friday.