Peter Hutton’s side were still licking their wounds after their controversial exit from the FAI Cup by Longford Town last Monday evening.
And Waterford, who were gathering some momentum before tonight’s game, were favourites to come away with an away result.
However Harps got stuck in and grabbed all three points when Killea man McHugh netted after 34 minutes before a poor crowd of less than 300 fans.
Harps restricted Waterford to not a single shot on target in the first half, while the United back-line had to be on their toes to contend with a feisty Harps attack.
The visitors eventually came to life in the last quarter of an hour as Seamus Long fired over the ‘bar from four yards out, before the full-back was then denied by a superb save from Ciaran Gallagher right at the death.
Harps showed two changes to the side that exited the cup on Monday night, with Kevin McHugh returning from suspension while Blaine Curtis came into partner him in what was the youngster’s first competitive start for the Donegal side.
And what an impact he made alongside the experienced attacker, linking up superbly as if they had been playing together for years. McHugh’s guile and finesse coupled with the sheer energy and enthusiasm of Curtis made life hell for the Waterford back-four, who were caught napping on a couple of occasions.
Curtis nipped in ahead of Kevin Murray on sixteen minutes before curling an ambitious effort just beyond the far upright, while Tommy Bonnar fired inches past the base of Kevin Burns’ left-hand post in a bright opening for Peter Hutton and Felix Healy’s men.
Harps, without a win since their sole triumph of the season against Athlone three weeks ago, were the side doing all the pressing, with goalkeeper Ciaran Gallagher, surprisingly, a virtual spectator in the opening forty-five minutes.
The breakthrough came eleven minutes before the break when Aaron McElwee showed great awareness to pounce on a slack goal-kick from Burns – the diminutive midfielder laying off to McHugh, who drilled beyond Burns with a composed strike from the edge of the area.
The second period was a lot more subdued, with neither side really showing too much bite or invention going forward.
The south-easterner’s had a couple of half-chances go a begging through the normally lethal Willie John Kiely, who never received the ball he would have liked all night.
Seamus Long then found himself all alone in the box with pretty much the last kick of the game but found Gallagher in no mood to concede, as the Harps ‘keeper pulled off a Schmeichel-like save at the end.
Finn Harps: Ciaran Gallagher; Paddy McLaughlin, Packie Mailey, Keith Cowan, Gareth Harkin; Mark Forker, Aaron McElwee, Tommy Bonnar, Marc Brolly; Kevin McHugh, Blaine Curtis. Subs: Garbhan Friel (Curtis, 82 mins), Ciaran Coll (Harkin, 90 mins).
Waterford United: Kevin Burns; Paul Carey, Kenny Browne, Kevin Murray, Seamus Long; Gary Keane, Gary Dunphy, David Breen, Conor Sinnott; Paul Murphy, Willie John Kiely. Subs: Shane Dempsey (Breen, 59 mins), Adam McSharry (Carey, 68 mins), Dwayne Wilson (Dunphy, 78 mins).
Referee: Darren Coombes.