Colchester United U23s inflicted a first defeat in eight on Millwall on Tuesday afternoon, after an impressive first half display.
They raced into a two goal lead at The Den, and were three up at the break.
The Lions pulled it back to 3-2 with ten minutes to go, but the U's held on to record their second win of the season.
The U's broke the deadlock after just five minutes, as Louis Dunne bent home a fantastic free kick from 25 yards.
And one quickly became two when Eoin McKeown slotted home to double the visitors' advantage.
The U's were in dreamland not long before half time, when a triallist swept a third past the keeper to extend the lead and put them into a commanding position.
The home side had it all to do in the second half, but gave themselves hope just before the hour mark when Harvey lobbed Barnes to reduce the deficit.
With eight minutes to go, it was 3-2 as Olofe finished from close range.