After a slow start to the game and a few feisty tackles being flown in, it was Coleraine who took the lead as a neat build-up presented the ball into the path of Darren McCauley.
The midfielder took a touch inside and fired an arrowed shot under the body of Elliot Morris and into the net.
On 17 minutes, McCauley will feel he should have added his second as a defensive mistake in the Glentoran penalty area resulted in the former Institute man firing over from outside the box.
It took until midway through the first-half for Ronnie McFall’s men to get into the game and their first meaningful effort arrived on 26 minutes. A lovely delivery from Ross Redman landed at the head of Marcus Kane but the Glens captain failed to hit the target.
The visitors were then on the front foot and nearly found an equaliser through a familiar source.
Striker Curtis Allen played a neat one-two with Alex O’Hanlon and his lobbed effort went narrowly over the bar.
However, Glentoran were left wondering how they weren’t on level terms at the break as Robbie McDaid had a header cleared off the line, before the summer signing had a shot acrobatically saved by Chris Johns.
The Glens made a blistering start to the second-half and had the Bannsiders camped inside their own half.
The only telling chance that arrived from that early pressure arrived when McDaid blazed over the bar from an acute angle as Coleraine failed to clear their lines.
The East Belfast side were nearly rewarded for their dominance when a fine run from Steven Gordon found Allen and the striker’s instinctive shot just sailed inches by the far post with Johns beaten.
At the other end, Coleraine finally created a chance as McCauley was thwarted by Morris on two occasions.
The Bannsiders thought they had secured their passage into the semi-final on 84 minutes as sweet half volley by Brad Lyons looked destined for the net, but Morris palmed away his effort.
However, it wasn’t to be Allen’s night against his former club as he missed another guilt-edged opportunity to level the scores. A fantastic cross by substitute Dylan Davidson picked out the striker but he headed wide with the goal at his mercy.
McFall’s men would be left kicking their heels in frustration a minute later as Davidson found Gordon but he hit straight at Johns.
Incredibly Allen and Dan Kelly missed further chances as Coleraine book their spot in the semi-final of the Irish Cup.
COLERAINE: Johns, Kane, Harkin, McCauley, Bradley, Carson (Parkhill ’73), McConaghie, Lyons, O’Donnell, Traynor, McGonigle (Burns ’65).
Subs Not Used: Doherty (GK), Mullan, Douglas, Ogilby, Smith.
GLENTORAN: Morris, Kane, Birney, Addis, McGuigan, Allen, Kerr, O’Hanlon (Kelly ’82), Gordon, Redman, McDaid (Davidson ’78).
Subs Not Used: Nelson (GK), McMullan, Nelson, Ferrin, McCawl.