Ruairi Keating’s second-half winner for Finn Harps condemned Waterford United to a 1-0 defeat at Finn Park last night.
The Blues created plenty of chances to get the points that would have kept them in the chasing pack behind leading trio Shelbourne, Galway and Longford Town.
However, Keating – who is on loan from Sligo Rovers – settled the contest in the Donegal side’s favour with his sixth goal of the campaign.
The striker’s telling intervention arrived eight minutes after the break when he availed of a defensive mix-up to advance into space and bury the winner past Kevin Burns.
Brian Nolan was close to grabbing a late draw for the Blues, only for a Conor Winn to deny him by producing a smart save.
Meanwhile, Shelbourne got their business done early against Wexford Youths at Tolka Park to win 3-0 and reaffirm their position at the top.
Dylan Connolly fired the Reds into a fourth minute lead by cutting in from the right before Jake Donnelly made it 2-0 on 31 minutes.
It was 3-0 four minutes before the break when Willo McDonagh converted a re-taken penalty.
Both sides finished with 10 men as CJ Browne and Lee Murtagh picked up two yellow cards each.
Longford Town maintained the pressure on Shels by inflicting a 3-0 loss on Galway at Eamonn Deacy Park.
Two first-half goals from Don Cowan (11 minutes) and Mark Salmon (40 mins) put the visitors in control.
Any prospect of Galway staging a late comeback was dashed on the hour when Gary Shaw beat Conor Gleeson with a shot from the edge of the box.
The victory ensures Town remain within two points of Shels with a game in hand over the leaders.