Shelbourne advanced to their first final since 2011 as Adam Evans' first-half goal was enough to take them past St Patrick's Athletic in the Leinster Senior Cup semi-final at Richmond Park.
Evans kept a cool head in the midst of a flurry of penalty-box activity to set up a final date with either Dundalk or UCD next month.
It was the Premier Division side who had the lion's share of the play until the goal as they came out of the blocks firing with Darragh Markey and Alex O'Hanlon lively in midfield.
And they could have led within 60 seconds as Aidan Collins attempted to cut out a through ball and inadvertently turned the ball past goalkeeper Dean Delany, but the ball mercifully rolled wide.
The reprieve didn't last long, as Alex O'Hanlon's corner was met in the six-yard box by the head of Ciaran Kelly, whose downward bullet header looked destined for the net only for Delany to miraculously stop it on the line.
Shels' first opportunity came four minutes later as Dylan Kavanagh teed up Dayle Rooney just outside the box and the teenager's left-footed effort was just a little too close to Lucasz Skowron.
Pats had the majority of the possession in the early stages but Shels looked more incisive on the ball, and it wasn't entirely unexpected when they took the lead on 14 minutes.
An almight scramble in the box, which saw a number of shots blocked at close quarters, ended at the feet of Adam Evans and the striker unceremoniously lashed the ball into the net from six yards.
Saints should have been level within two minutes as Alex O'Hanlon evaded an attempt to play offside and tried to casually lob Delany, but there wasn't enough loft on his effort to beat the keeper.
It was the second of three chances for the former Liverpool trainee in the space of 60 seconds, with the final effort blasted over from the corner of the box.
Darren Dennehy – playing his first game after a five-month lay-off with a foot injury – should have equalised when Kurtis Byrne's free kick was let bounce in the box but he put the ball over.
Shels had more of the ball as the half drew to a close but created little other than a succession of blocked crosses, with a Derek Prendergast header wide the clearest opportunity.
The second half continued in much the same vein as the first with Pats seeing more of the ball but Shelbourne creating more limited, but better, opportunities.
Kavanagh's spectacular effort on the hour forced the backpedalling Skowron to parry over the bar, and another similar effort saw the 'keeper spill the ball in front of him to Rooney.
The 18-year-old thought he'd managed to find the bottom corner when he eventually dug the ball out of his feet only for Skowron to stick a long arm out to halt the ball's momentum.
Just after James Brown did well to put Turner's cross behind, Alex O'Hanlon's subsequent corner was headed narrowly over by Rory Feely.
Liam Buckley introduced Christy Fagan and Conan Byrne in an effort to spark some creativity, but it was another sub, JJ Lunney, whose cross nearly forced Prendergast to head into his own net.
And it was the reflexes of Aidan Collins that denied Conan Byrne a last-minute equaliser as he lifted a leg to deflect the winger's header off the line.
St Patrick's Athletic: Lucasz Skowron; Michael Barker (Christy Fagan 68), Darren Dennehy (JJ Lunney 46), Ciaran Kelly; Jamie Lennon, Alex O'Hanlon, Darragh Markey, Kurtis Byrne, Ian Turner; Josh O'Hanlon (Conan Byrne 70).
Subs not used: Brian Maher (gk), Cian Hughes, Richie O'Farrell, Graham Kelly.
Shelbourne: Dean Delany; James Brown, Aidan Collins, Derek Prendergast, Sean Byrne; Alan Byrne, Mark Hughes, David O'Leary (James English 72), Dylan Kavanagh, Dayle Rooney (Dylan Grimes 89); Adam Evans.
Subs not used: Jamie Quinn (gk), Aaron Molloy, James O'Brien, Niall Lanigan, Chris Lyons.
Booked: Dylan Grimes (90+1).
Referee: Ben Connolly.
Attendance: 500 (estimate).
Extratime Player of the Match: Dayle Rooney (Shelbourne).