David Scullion's last-gasp equaliser gave the Bannsiders a dramatic Premiership draw at the Oval.
Aaron Boyd fired home the opener on his Coleraine debut but former Bannsiders star Stephen Carson levelled after a blunder from keeper Gavin Cullen.
Ex-Glens winger Scullion put Coleraine back in front with a shot on the turn but Carson equalised on 56 minutes.
Richard Gibson's cool finish gave Glentoran a final-minute lead, only for Scullion to head home in injury-time.
Scullion finished on the rebound after Boyd crashed a close-range header against the crossbar.
Gibson joined Carson and Scullion in scoring against their former club and his pinpoint strike from long range would have been a worthy winner.
It was Roy Coyle's last game as Glentoran temporary boss and new manager Eddie Patterson will be in charge for Tuesday night's league match against Donegal Celtic.