Luton too strong for U's in First Round tie.
Despite dominating the opening exchanges, the U’s found themselves 3-0 down at the break.
Freddie Hinds gave Luton the lead on 20 minutes, before a quickfire double at the end of the first half from Kavan Cotter and a Joe Tennent own-goal handed Paul Driver's side the initiative.
Louis Dunne's 59th minute effort proved to be only a consolation in a much improved second half performance.
Colchester started the game the brightest, taking the game to their hosts, who have won 14 out of their first 15 games this season and drawing the other. And Town goalkeeper Liam Gooch was tested after just three minutes, getting down well to keep out Tariq Issa's powerful, low drive from just inside the area.
The U's continued to dominate possession although poor passing in the final third ensured clear-cut chances were at a premium for Wayne Brown's side.
The Hatters, on the other hand, have been ruthless in front of goal in recent times – scoring 13 goals in their last five games, and Hinds grabbed his third goal in three games as he latched onto Alex Atkinson's through ball, following a sliced clearance by Tennent, before cutting in from the right and curling his shot past Callum Robinson.
The hosts then seized the upper hand with two goals in seven minutes to send Driver's side in at the break with a commanding lead.
The second goal came on 32 minutes thanks to some sublime build-up play.
Intricate passing on the edge of the Colchester box opened up the U's defence and sent Cotter free down the right.
The midfielder had time to compose himself before drilling a cross along the face of goal – only for the luckless Tennent to slide in and turn the ball into his own net.
Coming into the game, Luton were on an impressive run of ten straight wins in all competitions and, with confidence inevitably sky-high, the third goal came on 39 minutes to complete a quick-fire double.
Cotter was instrumental again, he made another driving run down the right before picking out the run of Atkinson in the box with an inch-perfect cross. Unmarked, the forward had time to pick his spot and smash the ball past Robinson from close-range.
Kyran McGhan-George was inches away from adding a fourth at the start of the second half, rising highest to meet Cameron McJannet’s free-kick from the right, but could only guide his header agonisingly over the bar.
Hinds then rattled the bar three minutes later. He benefitted from another incisive passing move inside the Colchester box before cutting in from the left, only to see his curling effort go out of play off the woodwork.
However, from the resulting goal-kick, the U's pulled a goal back through Louis Dunne.
A quick break-away down the left saw the Hatters defence carved open by a lovely through ball and Dunne beat the offside trap to surge into the box and slot past the on-rushing Gooch.
Colchester then began to enjoy a spell of rare dominance in the game and Ryan Clampin thought he'd halved the deficit on 70 minutes.
Good work from George Brown down the right saw the winger fire in a cross to the back post where Clampin was on hand to fire home on the half volley.
The linesman, however, cut short the celebrations, flagging for offside.
That was the last time the U's would seriously trouble the home defence, allowing Luton to hold on for a comfortable win, booking their place in the next round of the competition.