Longford Town 2 Derry City 1 (AET)
Alan Murphy scored a dramatic last minute winner in extra-time to put Town through to the final of the League Cup where they will meet St Patrick's Athletic.
With 120 minutes up on the clock Alan Kirby's free kick came back off the far post and Murphy scooped home the rebound.
Sean Francis had already scored a last minute equaliser in normal time to force extra-time.
Francis struck when he chipped home from an almost impossible angle right on 90 minutes.
The game looked destined to hinge on one incident on 23 minutes when Town conceded a sloppy goal and had midfielder Brian Byrne sent off.
Town skipper Barry Ferguson's misdirected back header to keeper Mick Dempsey came back off a post and Padraig Moran tapped the loose ball home.
Byrne was then immediately shown a straight red card by Cork referee Anthony Buttimer for dissent.
But 10-man Town hit back in style, though they left it late on the double.