Finn Harps delighted the majority of fans in a 4,000 strong crowd at Finn Park as they gained a major advantage in the first leg of the eircom League promotion/relegation final.
The First Division outfit fully deserved their win and must now be fancied to play in the top flight next season.
Harps went into the game knowing that they had to overcome their dreadful record in these play-offs, dating back to 1994 when they lost to Cobh Ramblers. Since then, the Donegal side has also come off second best in promotion/relegation clashes with Athlone Town, Longford Town, Galway United and Derry City.
Waterford, likewise, went into the game with a poor record in such matches, having never won a play-off series in four attempts.
After a tame start, the game sprung into life with Harps making the breakthrough in the 18th minute with long serving centre-half Declan Boyle powerfully heading home for his ninth goal of the season.
The goal really lifted Harps and with captain Tony Shields dominant in midfield the Paul Hegarty managed side put Waterford under a sustained period of pressure.
But Waterford went closing to drawing level on 34 minutes. Dave Mulcahy surged forward before finding Dave Warren who was taken down right on the edge of the box. From the resulting free, Warren's thumping effort was deflected out for a corner.
Harps continued to hold the upper hand after the break with Conor Gethins having two shots on goal while Michael Funston had a shot blocked.
Waterford were then reduced to ten men when Patrick Flynn received a straight red after a touch-line flare-up on 61 minutes, and two minutes later Harps made it 2-0 with Gethins lobbing the 'keeper from outside the box.
Harps then piled on the pressure and Gethins hit the post before Stephen Parkhouse added the third in the 87th minute following a free.
The second leg takes place in Waterford on Friday.
Finn Harps: Gallagher, McLaughlin, Minnock, Boyle, Holmes. Shields, Funston, McGowan, Parkhouse, Gethins, Brolly.
Sub: Divin for Brolly (71 mins)
Waterford United: Delaney, Flynn, Hedderman, Hayes, Breen, Warren, D. Mulcahy, McCarthy, Kearney, Kiely, Scully.
Subs: A. Mulcahy for Scully (45 mins), Brown for Breen (66 mins), Lordan for Kearney (72 mins).
Referee: Mr. Paul Tuite (Dublin)