JAMES Costello might have edged the visitors in front early in proceedings when he beat David Howland to the ball to find himself one-on-one with 'keeper Elliot Morris only for the home custodian to to save the danger with his left-foot.
Morris' opposite number, Wayne Drummond, did equally as well after half-an-hour when he palmed a first-time Sean Ward 35-yard right-footed drive onto the bar.
But the deadlock was broken five minutes after that when Howland headed home after Jimmy Callacher had knocked a right-sided Stephen Carson corner into his path.
United might have levelled six minutes after the break when Allan Jenkins stuck a leg out to reach a Gary McCutcheon cross only for Morris to produce a superb reaction save.
The visitors did equalise on 61 minutes, though, after McCutcheon got the final touch after the home defence failed to properly clear after a goalmouth scramble.
McCutcheon struck again ten minutes later to hand the Sky Blues the advantage but substitute Andrew Waterworth, only on the pitch five minutes, levelled for the Glens when he beat his marker to fire the ball beyond Drummond into the bottom corner.
But, with eight minutes left, United grabbed their third through Jenkins with a back post header after McCutcheon had teed his fellow Scot up.
Then, remarkably, two minutes after that McCutcheon outmuscled Ward to grab his hat-trick and maintain Ballymena's 100% away record.
Glentoran: Morris, Nixon, Ward, Howland, Carson, Hamilton, Gibson, Hill, McGovern, Callacher, O'Hanlon subs Hogg (not used), Clarke (not used), Taylor (not used), Waterworth (replaced Hamilton 72), Boyce (not used)
Ballymena United: Drummond, Kane, Gage, Stewart, McCutcheon, Jenkins, Teggart, Surgenor, Baker, Costello, Watson subs Vauls (not used), Murray (not used), Downey (replaced Watson 70), Smith (not used), Rodgers (replaced Surgenor 81)
- Gary McCutcheon celebrates one of his three goals at The Oval (Picture: Russell Pritchard/PressEye.com)