A dominant second-half wasn't quite enough for Blues Under-23sBCFC
Trailing 2-0 by the 19th minute, they came to life after the break and could so easily have snatched something from the game.
Corey O'Keeffe cracked a fine free-kick to fire the comeback and Charlie Lakin hit the crossbar.
But despite a much-improved display in the second-half, the damage had already been done.
Blues got off to a sluggish start and did themselves no favours by conceding a penalty after just seven minutes.
Steve Seddon up-ended Charley Edge after he tried to nip onto a ball set back to him by Eoin McKeown, who had his back to goal deep in the Blues area.
Tommy O'Sullivan stepped up and rolled the spot-kick to the right past Simon Lefebvre, who had gone the other way.
Blues then got caught by a press as they tried to pass their way across and out of defence. Lefebvre came to the rescue by getting down to make a parrying save from Tariq Issa's blasted shot.
It got worse for Blues when a ball down the middle forced Lefebrve to come to the edge of his area to try and stop McKeown in full flight.
He blocked the ball with his shins, sliding in to challenge, but it only came back to O'Sullivan who kept his calm to dribble on a few yards past the prostrate 'keeper and roll it into the unguarded net (19 minutes).
Blues eventually got going and Ronan Hale was not too far away from connecting with a volley from Olly Mulders lofted pass into the area.
But, still, they were not flowing in the usual way they can as the half passed the half-hour mark.
George Brown went close with a floated chip from outside the area after Blues were caught in possession again.
And, striding inside from right-back, executing a couple of stepovers as he cut past the Blues bodies, Kane Vincent-Young brought a save, low to the right, out of Lefebvre after letting fly from 22 yards.
Remeao Hutton whipped in an excellent cross after getting down the side of his opponent that was punched out in front of Hale by Daniel Wilks.
But Blues were not really creating coherent passages of play or telling combinations to consistently threaten the Us goal.
After one period of sustained pressure Colchester managed to break on them and McKeown drilled an attempt on the run from the right not far away from the inside of the opposite post.
Blues began the second period, unsurprisingly, with a bit of fire in the belly and pushed higher up the pitch.
Brown did very well to track Matthew Timms run to the left of the area to take a pass by Kyle McFarlane and stop him getting a cross or shot in.
And Blues went close in the 52nd minute when McFarlane took a short O'Keeffe pass inside the D, swivelled and whipped a shot away that just bounced past the post.
Hale next burst in down the right-hand side into a good position but unfortunately fizzed his drive into the near post side-netting.
Lefebrve made a very good tip-over save to deny O'Sullivan as Colchester relieved some of the pressure they were under in the opening quarter of the second period.
But back came Blues once more, this time Odin Bailey catching a 25-yarder nicely but seeing Wilks equal to it.
A goal had been coming and sure enough it arrived - spectacularly - via captain O'Keeffe.
Timms was tugged back as he tried to burst into the area and a free-kick was awarded, which O'Keeffe commanded.
From just outside the left angle of the box, he whipped a viciously curving shot that went round the wall to the 'keeper's side but beat Wilks for sheer pace on the ball (64 minutes).
Blues went close to equalising three minutes later when a cross from McFarlane was met at close range by Lakin, who adjusted his body to
usher it in with a sidefoot volley; but, no, Wilks got the slightest of touches on the ball to divert it onto the crossbar.
Only a brilliant block by Ollie Kensdale, throwing himself at McFarlane's hooked attempt from deep in the area, kept the home side's lead in tact as Blues continued to dominate proceedings after the break.
Blues, after Caolan Boyd-Munce's addition moments before O'Keeffe's goal, went to a 3-4-3 to try and press home their dominance and cause extra trouble for Colchester.
But as they pushed on they were caught on the counter and twice Lefebrve made good stops to keep the game on a knife-edge.
Blues fashioned another decent opening on the back of swift football on the edge of the area, but the 'keeper was again in the way as Bailey had a pop.
Blues kept going to the very end in forceful manner, but another goal just wouldn't come.
Blues: Lefebvre, Hutton, Seddon, Mulders, Timms (Boyd-Munce 64), Lakin, McCoy (Anderson 75), O'Keeffe, Hale, Bailey, McFarlane.
Not used: Weaver, Brown, Redmond.