Bluebirds take the points.
Colchester United's U21s fell to their first defeat of 2016 on Thursday against another in-form side.
Cardiff City had won three on the spin prior to taking on the U's and they came from behind to win 3-2 against John McGreal's men.
The home side had taken the lead after just nine minutes when Theo Warton snapped up a loose ball after former Col U loanee Rhys Healey had seen his shot saved.
Jack Curtis almost equalised six minutes later, before James Bransgrove made two good stops to keep the U's in the game.
Those saves proved important when the U's got level just before half time through a fantastic Charley Edge free kick.
And the visitors got their noses in front shortly after the break when recent first team debutant Femi Akinwande kept calm to slot home and make it 2-1.
The U's were on top at this stage, but were pegged back just after the hour mark when Kadeem Harris smashed home an equaliser.
And Cardiff completed the turnaround with eighteen minutes to go when Healey converted from the penalty spot to give the Bluebirds all three points.