A Ronan Coughlan brace eased Waterford to a routine win in Ballybofey over Finn Harps, who suffered a fourth successive defeat.
Connor Parsons and Dean McMenamy were also on target for Waterford, with Harps having defender Daithi McCallion sent off in the second half.
In March, Waterford put seven past Harps at the RSC and the scoreline here could have matched that were it not for a couple of big saves from home goalkeeper Tim Hiemer and a few spurned chances from the visitors.
While the evening unravelled for Harps after McCallion's dismissal in the 57th minute, Waterford were already well on their way to maximum points by that point.
Waterford - who recently added Alan Reynolds to the backroom staff as assistant head coach after a spell at Derry City - took the lead in the 25th minute. Hiemer saved superbly from April Player of the Month Coughlan but, with Parsons ready to pounce, Porter's attempted intervention saw the Harps defender put through his own goal.
Five minutes later, Waterford doubled their lead. Coughlan got too much time inside the area and the former Sligo Rovers and St Patrick's Athletic attacker delightfully curled beyond Hiemer to the bottom corner.
Earlier, Barry Baggley was inches from opening the scoring but his strike from distance rattled the underside of the crossbar before landing in the hands of the grateful Hiemer. It was one of those instances where, in the sport's more loftier stages, the opinion of VAR may well have been called for.
After the ever-lively Ryan Flood forced Paul Martin into a save following a good move down the right-hand side, Shane McMonagle was unable to get enough purchase when captain Keith Cowan recycled a set piece out on the left.
Waterford's quick-fire goals rocked Harps back on their heels and the hosts were under siege in the closing chapter of the opening period.
Hiemer was forced to claw over from a Shane Griffin header while McMonagle took the ball from the toe of Parsons, albeit at the expense of a corner, with the Waterford frontman looking set to apply the finish.
Michael Harris had started in place of Filip Da Silva but, the Convoy man having picked up a cut late in the first half, they switched at half-time.
Harps could have pulled one back eight minutes into the second half, but Sean O'Donnell was narrowly wide when he got his head on the end of Caoimhin Porter's cross.
With Harps down to ten men after McCallion saw red, McMenamy's stunning strike from long range gave Hiemer no chance just after the hour.
Waterford rubbed salt into the wound when, after Porter was harshly deemed to have fouled Parsons, Coughlan coolly slotted home from the spot.
With his first touch, sub Christopher Clarke had a chance to add a fifth, but McMonagle got a vital touch to thwart his efforts.
Seven minutes from the end, Hiemer spared further woe as he turned around the post from Coughlan.
Finn Harps: Tim Hiemer; Caoimhin Porter (Damian Duffy 78), Keith Cowan, Daithi McCallion, Shane McMonagle; Michael Harris (Filip Da Silva h-t), Noe Baba, Katlego Mashigo (Kevin Jordan 60), Seamas Keogh; Ryan Flood; Sean O'Donnell.
Waterford FC: Paul Martin; Niall O'Keefe, Giles Phillips, Killian Cantwell (Eddie Nolan 73), Ryan Burke (Tunmise Sobowale h-t); Shane Griffin (Christopher Clarke 73), Barry Baggley; Roland Idowu (Wassim Aouachria 72), Dean McMenamy, Connor Parsons (Thomas Oluwa 73); Ronan Coughlan.
Referee: Oliver Moran
Elsewhere, leaders Galway United maintained their 10-point advantage over Waterford with a 3-0 win at Treaty United.
David Hurley and Francely Lomboto gave The Tribesmen a 2-0 interval advantage and Ibrahim Keita added a late third after the hosts' Andrew Spain was sent off on a second yellow card.
Bray Wanderers leapfroged Cobh into third place with a 2-0 victory at Kerry.
Both goals came in the second half, from Harry Groome and Ben Feeney.
Cobh Ramblers were twice pegged back in a 2-2 draw at home to Athlone Town. Luke Desmond gave them a 25th-minute lead but Frantz Pierrot responded 10 minutes later.
Conor Drinan restored Cobh's lead in first-half injury-time but Matthew Leal earned a point for the visitors just after the hour.
Longford Town jumped above Wexford FC with a 3-0 demolition of the hosts at Ferrycarrig Park. New recruit Beinion O'Brien-Whitmarsh, brother of Cork City star Joe, struck the opener on 40 minutes, Josh Giurgi doubling their lead on the stroke of half-time.
O'Brien-Whitmarsh, who signed from Cobh last Sunday, made it a debut to remember, sealing the win with his second on 65 minutes.
