Finn Harps created the first chance of note on seven minutes when centre forward Tunde Owolabi got free inside the penalty area, but his shot was superbly kept out by Brian Murphy, before Phoenix Patterson had a chance at the other end two minutes later only to be denied by Ger Doherty.
It was Waterford that went in front on 19 minutes when Jack Stafford set up Junior Quitirna down the left before crossing into the area, and after Ryan Rainey’s clearance fell to Phoenix Patterson, he beat 'keeper Doherty with a sweet right-footed strike from 18 yards for his third goal in as many games.
The visitors called Murphy into action three minutes later when Jordan Mustoe sent in a free kick from the right that broke to the top of the penalty area for Shane McEleney, but his shot was straight at the Blues netminder.
Patterson went close to grabbing his second goal on the half hour mark when he stepped over a free kick 25-yards from goal after a foul on Junior Quitirna by defender Dave Webster, but his shot just cleared Doherty’s crossbar.
Doherty was forced off injured on 33 minutes after suffering a groin injury to be replaced by Mark McGinley, and after they forced four corners in a row, the Waterford defence held firm with a Jordan Mustoe free kick from distance two minutes before the break flashing inches over.
The Blues had a penalty appeal turned down three minutes into the second half when Anthony Wordsworth fired in a shot in from 25-yards that struck the hand of Shane McEleney, but referee Graham Kelly awarded a corner kick.
After Tunde Owolabi raced clear down the left flank into the area a minute later, Blues midfielder Shane Griffin got in a timely intervention to deny the striker a shot at goal, before Muscoe’s left-wing cross for the same player on 50 minutes saw his shot go just wide of the near post.
There was a hold up in play soon afterwards when Waterford’s Greg Halford was involved in an aerial clash with substitute John Dunleavy, and after a spell of treatment, he was able to resume his place in the Blues defence.
Shane McEleney kept Finn Harps in the game when he denied Phoenix Patterson a certain second goal on 66 minutes when he took a pass from Shane Griffin out on the left-side, but his goalbound effort was superbly blocked.
Waterford doubled their lead on 69 minutes when Kyle Ferguson’s long ball out of defence saw Harps keeper Mark McGinley race out, and Junior Quitirna nipped in to slip the ball into the empty net from the right-side of the area.
Waterford keeper Brian Murphy was sent off after striking out at Harps defender Kosovar Sadiki as he tried to clear the danger, which resulted in a penalty on 72 minutes, and although Matt Connor guessed the right way, he couldn’t keep the spot kick from Tunde Owolabi out.
With a nervy RSC hoping their side would hold out for victory, it got even better when they scored two goals of quality in the dying minutes.
Junior Quitirna turned provider for John Martin for a third goal after a super run, before the former completed the scoring with a magnificent goal.
Goal number four was the icing on the cake - Jack Stafford started the move down the left-side before setting up Phoenix Patterson, who played the ball inside for Anthony Wordsworth before taking the return pass to set up Junior Quitirna, and he powered a left-footed strike past McGinley to send the Waterford crowd wild. Oh what a win.
WATERFORD FC: Brian Murphy, Greg Halford, Kyle Ferguson, Eddie Nolan, Jack Stafford, Anthony Wordsworth, Shane Griffin (Matt Connor ’74), Niall O’Keeffe, Phoenix Patterson, Junior Quitirna, John Martin.
FINN HARPS: Ger Doherty (Mark McGinley ’33), Shane McEleney, Dave Webster, Kosovar Sadiki, Jordan Mustoe, Karl O’Sullivan, Mark Coyle, Ryan Rainey, Adam Foley, Tunde Owolabi, Dan Hawkins (John Dunleavy ’46).
Referee: Graham Kelly (Cork)
