Two strikers goals from Gorman either side of half-time had Shelbourne in control before Kevin Dawson added a third and Ben McLaughlin put through his own goal.
The sodden surface after the daylong rain soon played its part in the first opening of the night. As players regularly lost their footing, the first chance fell Dundalk’s way on 14 minutes only for Paddy Kavanagh to make a good save at full stretch from Cherrie.
Shelbourne were bossing the game now and Philly Hughes wasn’t far off with a free-kick from distance before they deservedly took the lead on the half hour.
Hughes worked a one-two with strike partner Philly Gorman to bring a fine parry save from Cherrie. But Gorman was alert to the rebound to follow up and score with a stooping header.
When Cherrie was beaten again from Gorman’s header from a Kavanagh corner, right-back Paul Walsh was perfectly positioned to hack clear off the line.
Shelbourne remained well in control into the second half and doubled their lead seven minutes in.
Terrific full-back play down the right by Gareth Matthews saw him beat his man and deliver a sublime cross which Gorman headed home with Cherrie rooted to the spot.
Gorman completed his man-of-the-match display with a delightful first time flick for the run of Dawson on 63 minutes. And the midfielder ran through to casually rifle the ball low to the net at Cherrie’s left-hand post.
Substitute defender McLaughlin unwittingly put through his own goal to gift Shelbourne their fourth goal on 71 minutes. Dawson’s fierce drive was totally miscued, but it hit the right-back on the knee to ricochet to the back of the net.
SHELBOURNE: Bennion; Matthews, Hurley, Boyle, Fitzgerald; Cassidy (C. Byrne 75 mins.), Dawson, Sullivan (P. Byrne 82.), Kavanagh (B. McGill, 65); Hughes, Gorman.
DUNDALK: Cherrie; Walsh, Foran, Burns, Osborne; Mountney, Shields, McDonnell (McLaughlin, h/t), Waters (Brady, h/t); Rafter (Reilly, 67), Griffin.
Referee: Alan Kelly (Cork).