Glentoran moved to within four points of Premiership leaders Linfield with their second league victory of the season over their Belfast rivals.
Gary Hamilton scored the opening goal in added time at the end of the first half when he flicked the ball home with his right foot from 10 yards out.
Philip Lowry and Rory Patterson went close to equalising in the second half.
Hamilton grabbed his second a minute from the end when his right-foot free-kick was deflected past Alan Blayney.
The Glens received a boost before the game when striker Hamilton was passed fit to play after receiving a painkilling injection on his injured toe.
The first half was a scrappy affair of few chances but Jim O'Hanlon almost broke the deadlock on 21 minutes when Blayney lost the ball, but the young winger could only find the sidenetting from a tight angle.
Patterson saw his left-foot drive well saved by Elliott Morris, before the Glens took the lead.
Stephen Carson cut in from the left and crossed the ball into the penalty area, where David Howland dummied, allowing Hamilton to fire home.
Linfield began the second half brightly and Philip Lowry's glancing header was saved by Morris.
Another Lowry header sailed over the bar and Morris then pushed away Patterson's rasping left-foot effort.
Blayney saved a Hamilton free-kick and, at the other end, Morris dived to deny Patterson's goalbound looping header.
Carson fired a left-foot shot over the bar, before Hamilton made the three points safe with his free-kick.
Carson almost added a third but his late attempt was pushed round the post by Blayney.
Linfield top the league on 33 points, with Portadown second on 31 and the Glens and Cliftonville third on 29 points, Glentoran enjoying the better goal difference.