Dangerous David Scullion earned Glentoran the three points at Mourneview Park - but they had to hold on for dear life to get the 2-1 win.
The winger set up the Glens their opener on 21 minutes, swinging in a corner which Andy Coleman flapped at. That left David Howland free to volley home.
The former Coleraine man doubled the lead 10 minutes into the second half, sidefooting the second after Stephen McAlorum had pulled the ball back from the byline.
Glenavon huffed and puffed all day and saved their best until last, getting a goal back when Gary Hamilton’s corner hit the post and rebounded in off Andy McGrory. They, however, will rue the fact that despite having plenty of attacks they failed to turn them into chances.