National League Premier Div/Shelbourne 5 Waterford United 1: It needed the spark of Bobby Ryan's stunning opening goal, but once Shelbourne found their range in the second half they cruised back to the top of the table with plenty to spare.
The win, their sixth straight victory in the league, moves Shelbourne ahead of champions Cork City on goal difference, though they also have a game in hand.
It did not look good for bottom-of-the-table Waterford from the start. New signing Paul Hopkins couldn't make his debut as his registration hasn't come through yet.
Alan Reynolds, who returned to Waterford from Shelbourne last week, was ineligible as part of the terms of his move while James Chambers, who is on loan from Shelbourne, couldn't play either.
To add to Waterford's woes, Kenny Browne, their goalscorer in Friday's 2-1 defeat to Sligo, failed a fitness test.
A dour first half needed a glint of genius to bring it to life and it thankfully arrived in stoppage time.
Ryan took Ollie Cahill's pass, dropped his right shoulder to throw off a defender and curled a delightful shot into the top corner of Ben Spicer's net.
That papered over the cracks of a less than inspiring first half for Shelbourne. But Pat Fenlon's side were much better on the resumption and tore Waterford apart.
John Hayes made a superb goal line clearance to deprive Jason Byrne from Cahill's cross on 59 minutes before Shelbourne added their second goal one minute later.
Glen Crowe's header from Joseph Ndo's corner was stopped on the line, but central defender Colin Hawkins was there to blast home the rebound.
Substitute Mitchell Casey stunned Shelbourne when pulling a goal back within a minute, side-footing home Gavin Doyle's cross.
But normal service was resumed within a further two minutes when Jason Byrne somehow kept the ball in play from Crowe's cross for Ndo to score for the third match in succession
Byrne then put Crowe through on goal on 67 minutes and he had little difficulty in adding the fourth goal.
Crowe wasn't finished yet, though, and he got his second of the night in the 91st minute.
SHELBOURNE: Delaney; Heary, Hawkins (Harris 77 mins), Dillon, Rogers; Ryan (Baker 77 mins), S Byrne (O'Halloran 54 mins), Ndo, Cahill; Crowe, J Byrne.
WATERFORD UNITED: Spicer; Flynn, Deans, Hayes, Young (Russell, 26 mins, Casey half-time); Fraher (Poleczak 80 mins), Grant, Hughes, Kavanagh, Irwin; Doyle.
Referee: D Hanney (Dublin).