David McMillan's first-half strike proved enough for Dundalk to see off Finn Harps at Oriel Park to move up to sixth place in the SSE Airtricity League table.
On the back of their Europa Conference League victory away to Newtown on Tuesday, Vinny Perth's side bossed the first half without ever really making their dominance count.
However, McMillan’s goal saw them move to within three points of fourth placed Bohemians, albeit with a game more played.
The Co Louth men were almost made to rue their failure to press further ahead when on top as Ollie Horgan's visitors grew more into the game in the second half.
They were unable to really trouble the Dundalk rearguard as the home side held out comfortably for a deserving victory ahead of Thursday's second qualifying round first leg tie against Levadia Tallin in Tallaght.
For the Ballybofey men it is now three defeats on the trot with just one point taken from the last 18 on offer with no wins in nine since beating Waterford FC 2-1 away from home on 24 May.
It was one-way traffic from the off at Oriel Park with the home side having a big early chance on four minutes when Daniel Kelly found space on the right to pull back to Will Patching who blazed over from close range.
Raivis Jurkvoskis then went close with a volley following a crossfield pass from fellow full back Darragh Leahy before McMillan had a header blocked on the line on 14 minutes from Michael Duffy's corner.
Sonni Nattestad should have broken the deadlock five minutes later when he was picked out virtually unmarked six yards out by a brilliant Patrick McEleney pass but somehow the Faroese centre-half managed to steer his effort wide.
McMillan and Jurkovskis then both went close with headers before the breakthrough finally arrived on 33 minutes with both players having a big part to play in it.
McEleney did well to release Jurkovskis on the right. The Latvian international saw his shot saved by Mark McGinley but the goalkeeper was unable to hold it with the loose ball falling invitingly to McMillan to bundle home his 90th goal in Dundalk colours from all of four yards out.
Finn Harps would create their first chance of note four minutes before the break when Kosovar Sadiki beat Nattestad to get his head on Karl O’Sullivan’s free kick but he couldn’t get any sort of power on it to trouble Alessio Abibi.
The Donegal side did improve on the restart and perhaps should have levelled on 59 minutes when Abibi failed to deal with Barry McNamee’s corner under pressure from Sadiki but no one was on hand to punish the error.
New signing Dan Hawkins then almost had an opening four minutes later when the ball broke to him in the box but he couldn’t get a shot away to trouble the Albanian keeper.
Moments later Adam Foley - who had scored a double in the win away to Dundalk back in March - looked like he had got in behind but failed to connect properly with his effort and injured himself in the process leading to Tunde Owolabi replacing him.
McNamee then had an effort from range on 74 minutes but it was straight at Abibi.
McMillan then had a big chance to seal the game three minutes later after being slipped in by McEleney but his effort was saved by the outrushing McGinley and while the richochet took the striker past the keeper, Ethan Boyle was on hand to clear his lines.
Duffy then had an effort blocked down by Jordan Mustoe with Harps’ best chance of an equaliser coming in the fifth minute of stoppage time when Owolabi headed harmlessly wide from Boyle’s cross.
Dundalk: Alessio Abibi; Raivis Jurkovskis, Andy Boyle, Sonni Nattestad, Darragh Leahy; Sam Stanton, Patrick McEleney; Daniel Kelly (Val Adedokun 93), Will Patching (Wilfried Zahibo 87), Michael Duffy; David McMillan (Ole Erik Midtskogen 79).
Finn Harps: Mark McGinley; Ethan Boyle, Dave Webster, Kosovar Sadiki, Jordan Mustoe; Karl O’Sullivan (Ryan Connolly 88), Mark Coyle (Sean Boyd 80), Will Seymore, Barry McNamee (Ryan Rainey 88), Dan Hawkins; Adam Foley (Tunde Owolabi 68). Subs not used: Ger Doherty, John Dunleavy, Shane McEleney, Conor Barry, Stephen Doherty.
Referee: Rob Harvey (Dublin).