Cork City ended Derry City's treble ambitions by claiming a 1-0 victory in Tuesday's Setanta Cup semi-final.
After a scrappy first half, Timmy Kiely headed Cork's winner on 68 minutes.
Derry had a strong penalty claim turned down on 77 minutes after Mark Farren appeared to be bundled over in the box by Cork goalkeeper Mark McNulty.
Farren had a close-range chance blocked as Derry produced late pressure but Cork held on to claim a place in the final against Glentoran on 1 November.
Derry struggled to find fluency throughout the contest as they slipped to their second successive defeat after Friday's league reverse against Bray.
The Candystripes forced a succession of early corners as they started brightly but despite a lot of endeavour by the home side, they didn't produce a decent chance in the opening period.
Danny Murphy went close for Cork on 32 minutes and Joe Gamble then wasted the best first-half chance when he pulled a snapshot wide.
The game became bogged down in a midfield battle in the third quarter although Farren had a half-chance blocked in the 61st minute.
Cork's winner came seven minutes later after impressive centre-back Dan Murray charged down the left wing and produced a pinpoint cross which Kiely powered past Gerard Doherty.
Derry did look decidedly unfortunate not to be awarded a penalty by referee David Malcolm on 77 minutes after keeper McNulty appeared to foul Farren.
Farren had a late chance as Derry pressed in the closing minutes but he delayed his shot and Danny Murphy got back to make a vital block.
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