THE Swifts started brightly and might have grabbed a 6th minute opener only for Michael Funston to fail to get the necessary strength to a header following a Robert Robinson fumble.
Then, on 23 minutes, PJ Lavery thought he had scored only to see it ruled out offside.
However, just a matter of minutes after that, Dermot McCaffrey did break the deadlock with a tremendous 25-yard drive which gave Robinson no chance.
It got worse for DC moments from the break when Niall Atkinson was dismissed by referee Mervyn Smyth for a two-footed foul on Stefan Lavery.
Despite this Celtic might have levelled on 65 minutes only for Johnny Gowdy's 20 yard drive to connect with the crossbar.
Michael Ward made sure of the points for the Swifts with six minutes remaining with a successfully converted penalty.
Donegal Celtic: Robinson, Keegan, Harkness, McNamee, M. Burns, Lambe, L. Bradley, Lynch, D. Murray, McAllister, Gowdy subs Atkinson (replaced Harkness 8), Glenholmes (replaced Lambe 85), Fay (replaced Lynch 67), P. Bradley (not used), Muir (not used)
Dungannon Swifts: Morgan, O'Neill, Montgomery, McCaffrey, McClean, Fitzpatrick, Topley, Murphy, S. Lavery, Ward, P.J. Lavery subs Campbell (replaced S. Lavery 26), McGerrigan (not used), McMinn (not used), Funston (replaced Topley 6), McCready (replaced PJ Lavery 56)
- Terry Fitzpatrick shields the ball from Jody Lynch (Picture: Jonathan Porter/PressEye.com)