Waterford lifted themselves off the foot of the SSE Airtricity League Premier Division table with a first win at Oriel Park in over 18 years.
A John Martin brace either side of a Shane Griffin strike saw the Blues come from behind to ensure a first victory under new boss Marc Bircham after Patrick Hoban had given the home side a 31st minute lead from the penalty spot.
Not since January 16th 2003, 6,772 days earlier, had Waterford won at Oriel Park when Daryl Murphy's 81st minute goal earned a 1-0 win in the last of the old winter seasons before the move to summer football.
The victory - just their third of the season and their first in eight matches - sees them leapfrog Longford Town and was a welcome boost for new owner Richard Forrest, who was an interested onlooker following his recent takeover from Lee Power.
For Dundalk, it marks a new low in their already chaotic season as the managerless outfit slipped to a sixth defeat in 15 matches - two more than they suffered when winning the 2019 title when two of their losses came after the league was in the bag.
Jim Magilton now has a massive job to lift the side ahead of next week’s clash with Longford Town, but for Waterford and Bircham this result will hopefully be the start of a bright new era.
The visitors had the first big opening inside the opening 90 seconds when Martin was played through only to fire just over.
In a half of few chances it would take until the 14th minute for Dundalk to register their first when Hoban laid off for Greg Sloggett to get a shot away that flashed just over Brian Murphy’s crossbar.
Andy Boyle then headed just over from a Michael Duffy free-kick six minutes later before the Louth men were awarded a spot-kick on 31 minutes.
Hoban did well to slip Ole Erik Midtskogen away and the Norwegian was adjudged by referee John McLoughlin to have been pulled back by Cameron Evans as he made his way into the box.
Hoban then stepped up to fire in off the post to give his side the lead despite Brian Murphy going the right way.
It would be all square at the break, however, as John Martin was slipped in between Andy Boyle and Sonni Nattestad before calmly firing past Alessio Abibi.
Hoban then looked like he would restore Dundalk’s advantage on 54 minutes when he was picked out by Duffy before cutting inside onto his left foot to get a shot away but Kyle Ferguson did enough to deflect the effort over.
That was to prove crucial as Waterford took the lead on 62 minutes.
Referee McLoughlin played a superb advantage after Nattestad had caught Prince Mutswanguma with Darragh Power finding space on the right to square across to Griffin who slotted home from six yards out.
Patrick McEleney thought he would reply on 71 minutes after being slipped in behind but he was denied by a stunning stop from Murphy.
Martin put the result beyond doubt five minutes later after creeping in at the back post to slot home Jamie Mascoll’s cross from the left after a short corner.
The home side did push hard for a way back into the game after that but lacked the drive and quality to trouble a Waterford side who were full value for the three points.
Dundalk: Alessio Abibi; Cameron Dummigan, Andy Boyle, Sonni Nattestad, Val Adedokun; Patrick McEleney (Jesus Perez 88), Sam Stanton, Greg Sloggett (Sean Murray 72), Michael Duffy; Patrick Hoban, Ole Erik Midtskogen (Daniel Kelly 65). Subs not used: Peter Cherrie, Ryan O’Kane, Mark Hanratty, Junior, Han Jeong-woo.
Waterford: Brian Murphy; Darragh Power, Kyle Ferguson, Cameron Evans, Jack Stafford, Jamie Mascoll; Prince Mutswanguma (Eric Molloy 80), Shane Griffin (Cian Kavanagh 85), Niall O’Keeffe, Adam O’Reilly; John Martin. Subs not used: Matthew Connor, Paul Martin, Kallego Mashiga, Callum Stinger, Liam Kervick, Cian Browne.
Referee: John McLoughlin (Roscommon).