Glentoran came from behind to achieve their first Premiership win away to Coleraine since 2010.
Coleraine had gone into the lead just before half-time when Glentoran's Kevin Bradley turned the ball past keeper Elliott Morris for an own goal.
Jim O'Hanlon shot low for a 47th-minute equaliser and soon after that Mark Miskimmin ran through to make it 2-1.
Coleraine's Michael Hegarty was sent-off for a two-footed tackle before John McGuigan scored Glentoran's third goal.
Hegarty saw a straight red from referee Raymond Crangle for a lunge on young Glens player Jordan Stewart.
Coleraine defender David Ogilby saw a header strike the bar and the Bannsiders' hopes were ended when midfielder McGuigan forced the ball over after a good run by Stewart.
"Coleraine is a difficult place to come to at the best of times - but to win here with a depleted squad is a great result," said Glentoran manager Eddie Patterson.
"At half-time we felt we needed more urgency and those two quick goals after the interval put us in the driving seat."
Coleraine boss Oran Kearney said: "To concede those two goals early in the second half was criminal.
"I can't really pinpoint what went wrong - I am at my wits' end.
"It just disappointing in general because we have not learned our lessons from previous games."