Michael Duffy's first half goal proved the difference in the Louth derby as Vinny Perth picked up a first win in his second spell as Dundalk boss.
In the two games since his reappointment, Perth has relied on many of the players who formed part of his side prior to his departure in the summer of 2020. One of those, Duffy, once again assumed the role matchwinner in the derby.
His 35th minute goal was his seventh career strike against Drogheda, and his fifth in six league derby outings.
A third defeat in four has put the brakes on Drogheda's excellent start to the season. They didn't lack endeavour in the first league derby on Boyneside in a little over four years but they succumbed to their near neighbours for the second time this term.
The defeat, coupled with Bohs' Dublin Derby win, means Drogheda drop to fifth. Meanwhile, Dundalk climb once place to seventh and now are looking up the table rather than over their shoulder.
After their five-goal drubbing against Bohemians on Friday night, Tim Clancy replaced Ronan Murray and Jake Hyland with Killian Phillips and Luke Heeney.
Perth brought Faroe Islands international Sonni Nattestad into central defence, meaning Chris Shields was moved back into midfield where he partnered Greg Sloggett. Raivis Jurkovskis was also recalled.
The last time the Lilywhites played a league fixture at this venue, with Stephen Kenny in the dugout back in 2017, they ran out 6-0 winners. They have dominated recent Louth derbies but arrived in Drogheda in the usual position of sitting four places and seven points below their neighbours.
They knew they were up against early on as Drogheda, buoyed on by home supporters for the first time this season, started with real intent. However, for all their endeavour they failed to test Dundalk goalkeeper Alessio Abibi.
The visitors had the better chances and Pat Hoban was denied by David Odumosu at close range. Nattestad also headed over before the opener arrived.
Duffy met Patrick McEleney's cross with a fine header which Odumosu was at full stretch to keep out. He then saved from Daniel Kelly's follow-up but the ball squirmed loose to Duffy who slotted an effort through covering defender Daniel O'Reilly's legs.
Dane Massey had headed over from a set-piece before the break but chances for both teams were at a premium for the remainder of the game.
Clancy's side came on strong towards full time but really offered little threat. Darragh Markey's shot was straight at the Albanian stopper then James Clarke's late mazy brought through the centre of the Dundalk block opened a path to goal. But the youngster's shot failed to threaten the goal.
United have now gone two games without scoring for the first time this term, while things are looking up for Perth's Dundalk ahead of the visit of Derry City to Oriel Park on Friday.
Drogheda United: David Odumosu; James Brown, Daniel O'Reilly, Dane Massey, Conor Kane; Killian Phillips, Gary Deegan, Luke Heeney (James Clarke, 83); Darragh Markey (Jordan Adeyemo, 64), Mark Doyle (Ronan Murray, 64) Chris Lyons.
Dundalk: Alessio Abibi, Raivis Jurkovskis, Andy Boyle, Sonni Nattestad, Darragh Leahy (Cameron Dummigan, 59); Chris Shields, Greg Sloggett; Daniel Kelly (Sean Murray, 59), Patrick McEleney (Sam Stanton, 87), Michael Duffy; Patrick Hoban (Patrick Hoban, 73).
Referee: Graham Kelly (Cork)