A spectacular first-half strike from David Cassidy proved to be the difference between the sides in Tolka Park last night, as Shelbourne progressed to the second round.
The hosts started brightly and took the lead on 25 minutes when a Barry Clancy cross from the left was finished acrobatically to the net by Cassidy.
Mervue did start to close down Shels in the middle-third as half-time beckoned, but goalkeeper Brian O'Donoghue had to be at his very best to turn away an Anto Murphy header in first-half stoppage time.
Shels were on top in the possession stakes after the re-start, but that second goal was eluding them, despite Murphy going close with a back post header from a Cassidy set-piece on 66 minutes.
However, the single goal proved enough.
SHELBOURNE -- Delany; Shorthall, Paisley, Ryan, S Byrne; Murphy (McGill 67), Dawson, Sullivan (Hurley 86), Clancy; Cassidy; Gorman (Hughes 78).
MERVUE UNITED -- O'Donoghue; Varley (O'Rourke 81), Dravins, Walsh, Tully; Connolly (Farrell 88), McEntee, Hoban, Collins, Nkololo; Keegan.
REF - P Caschera (Dublin).