McIlmoyle struck on 48 minutes when he powerfully headed a Trevor McLernon free-kick into the bottom corner of Elliott Morris' goal.

It was no less than the Roesiders deserved after a first half which saw them trade chances with their more illustrious visitors.

The Glens created the first effort on six minutes when Michael Ward put Gary Hamilton through but his shot was deflected past an upright while at the other end saw his header from a Matt Crossan cross well saved.

Gareth Tommins had another header blocked on 28 minutes before, ten minutes after that, Morris' opposite number, Glenn Millar, did equally well to keep out a Kyle Neill free-kick that whistled through a crowded area.

Matthew Boyd might have doubled the Roesiders' advantage on 69 minutes when he got on the end of a McIlmoyle through ball only to fire over the bar followed seven minutes later when Gareth Tommins failed to get a touch to a Crossan free-kick which Morris had pushed out.

The best the Glens could offer in return was a couple of Paul Leeman long-range efforts and their cause was further weakened three minutes from the end when Neill was dismissed for deliberate handball.

Glentoran might have snatched a late equaliser right at the end of stoppage time but Hamilton pulled his effort the wrong side of the far post.