A goal in each half by Jermaine Beckford ensured that Leeds United came out on top in Saturday's top of the table clash.
The U's had started the game brightly but fell behind just before half time from a penalty and the home side confirmed the win with another from their prolific striker after the break.
Carlisle come to Colchester on Tuesday as the U's look to build another unbeaten run.
U's boss Aidy Boothroyd made the one expected change from the side that beat MK Dons in midweek, with John White replacing loanee Christian Ribeiro at right back.
On the bench, it was one new signing out and one new signing in, as Morten Knudsen came in as David Prutton dropped out. The Leeds loanee was ineligible for the game against his parent club, after scoring on his debut in Tuesday's 2-0 win.
Simon Grayson made five changes for the hosts, giving newest loanees Gary McSheffrey and Shane Lowry debuts.
How many of these changes were made with Tuesday's cup replay against Spurs in mind remained to be seen but the Leeds boss would have been well away of the threat the U's could pose.
The game started with a wintry sun bathing half the pitch and the U's looked like they were up for the challenge, with Anthony Wordsworth having an early shot blocked after good work by Phil Ifil.
Play switched quickly to the other end though and John White had to be quick to block after Okuonghae misjudged a clearance from deep in the Leeds half. It hit his back as he ducked under it and White covered behind Williams to avert the danger.
In the fifteenth minute, the U's should have had a penalty when Phil Ifil had his shirt pulled as he got free in the area but the referee waved away the appeals.
Four minutes later, Kevin Lisbie had a volley from the edge of the area saved before Ben Williams was in the right place to field a Doyle strike at the other end.
Ifil made Ankergren scramble across his line from a free kick that was drilled low past the Leeds wall but the Leeds keeper was equal to the task and saved at the foot of his post.
The home side went ahead on thirty seven minutes when Matt Heath challenge on Becchio was adjudged to be a foul and the referee pointed to the spot. Beckford stepped up and dispatched his twenty third goal of the season to give Leeds a 1-0 lead.
Williams had to be at his best to prevent Leeds going further ahead in the closing stages of the half, as he palmed away a McSheffrey shot.
The U's went into half time unlucky to be behind and would have been pleased with the way they went about their business in the first half.
The U's started the second half in a similar manner to the first, as Wordsworth had the first shot, but failed to hit target with his right foot effort.
Beckford was then in the thick of the action, having a shot saved then blocked a blistering volle form his teammate McSheffrey.
And it was the Leeds top scorer Beckford that settled the game shortly after as he tapped in at the far post after Howson shot rebounded off the woodwork.
The U's tried valiantly to get back but failed to test the home keeper and it was the home side who looked more likely to extend the lead.
Williams saved well to concede a corner in the eighty fifth minute and then Bromby hit the crossbar with a header but the score remained 2-0 and the U's remained in fourth place.