Finn Harps extended their unbeaten run to nine games when two first-half goals proved enough to kill off Kilkenny City on Saturday night. The defeat, Kilkenny's 21st of the season, means the club are relegated.
Harps broke the deadlock on nine minutes, when Niall Bonner set up Kevin McHugh, who finished well.
Two minutes before the break the Donegal side scored their second through Jonathan Minnock after a neat interchange with Fergal Harkin.
The win lifts Harps to within two points of UCD as the battle to avoid the drop goes down to the wire.
FINN HARPS: D Bradley; R Kenny, Minnock, Fitzhenry, S Bradley, Bonner, Mohan, J Kenny, Lloyd, McHugh, Harkin. Sub: Tierney for Mohan (89 mins).
KILKENNY CITY: Nelson; Wilkinson, Jackson, Purdy, Mulcahy, Brennan, O'Hanlon, McGrath, O'Byrne, Roos, Murphy. Subs: Comerford for Roos (48 mins); O'Neill for O'Hanlon (66 mins); Fennelly for Jackson (81 mins).
Referee: D McKeown (Dublin).