Five different players found the scoresheet for Trevor Croly's side, with Stephen McPhail coming off the bench to net on his debut
The game started in a high tempo fashion with the home side being denied a penalty as winger Gary McCabe was taken down by Glentoran defender, Jason Hill. However, referee Neil Doyle waved play on, much to the annoyance of the Rovers support.
Shamrock Rovers did however find themselves on the scoresheet early on as the wind helped Ciaran Kilduff to find the on-rushing Robert Bayly who hammered home a clean volley to put the home side in front.
Glentoran pegged Rovers back several moments later as John McGuigan’s deflected shot found itself past Barry Murphy, who was in the middle of diving to his right as he watched the ball fizzle into the left hand corner of the net.
Rovers restored the lead on the hour mark as former Bray Wanderers man Kieran Marty Waters struck a deflected shot which lopped over Glentoran goalkeeper Elliot Morris. Debutant Stephen McPhail got himself on the score-sheet as Rovers won a free-kick on the edge of the Glentoran box. Up stepped the former Sheffield Wednesday midfielder who fired his free kick into the left hand corner of the net.
Shamrock Rovers got their fourth of the night when Gary McCabe found space at the back post. The attacker caught the ball perfectly on a volley into the back of the net to put the home side even further ahead. Stephen McPhail found the run of Simon Madden who slotted home for Rovers’ fifth of the night in stoppage time.
Trevor Croly's side will travel to the Oval on March 17 for the second leg, holding a big advantage after an impressive display at Tallaght Stadium.