U's beaten by Posh on Saturday.
Colchester United's hopes of pulling clear of trouble were dealt a blow on Saturday afternoon, as Peterborough United ran out 4-1 winners at the Weston Homes Community Stadium.
As has been the case on a number of occasions this season, the scoreline didn't reflect the overall balance of the game and the U's will reflect on a day of what might have beens as they prepare for their next match.
Having fallen behind early on, they then missed a penalty as George Moncur was denied, Chris Porter's celebrations were cut short by the linesman's flag and, at the start of the second half, Elliot Lee hit the base of the post with a fine effort.
And, as they pressed for the equaliser, they not only came up against the highly impressive Ben Alnwick, they were also picked off by the visitors as the U's were caught with men upfield.
It leaves the U's with a huge task to pull clear of trouble now, sitting nine points behind with twelve to play for.
The home side fell behind after just two minutes as Jon Taylor bundled through to slot home past the helpless Elliot Parish.
The U's spent much of the rest of the half in Posh territory, and Elliot Lee won a penalty midway through the half.
He was felled in the area, but Alnwick turned away Moncur's spot kick to his left to preserve the visitors' advantage.
The U's kept pressing though and thought they had drawn level on 27 minutes as Porter helped Moncur's shot into the net, but was flagged offside.
Next, Elliot Lee saw one bend just wide, but Posh fired a warning shot across the bows as he forced Parish into a good stop eight minutes before half time.
The U's somehow found themselves behind at the break and, after a bright start to the second period, would be left wondering how they hadn't got level.
Lee drilled a low shot across the face of goal and it beat Alnwick, only to cannon back off the post.
The Posh keeper was in the right place, at the right time, to deny the U's before a quick fire double took the game away from the home side.
Manager Graham Westley introduced Fox and Coulthirst from the bench and both scored within five minutes of coming on.
First Fox was on hand after Shorey had blocked a shot to slot home the rebound, then Coulthirst was ready for Taylor's cut back to make it three.
The U's in turn made two changes of their own as they introduced Femi Akinwande and Macauley Bonne.
Bonne forced Alnwick into a save with his feet with his first effort and followed that up with another fine save as the U's youngster headed towards goal from close range.
But, from the resulting corner, Moncur lifted a shot into the net beyond the keeper to give the faintest glimmer of hope.
That hope was extinguished late in the game though as, after Parish had turned Taylor's shot onto the post, the visitors escaped on the counter yet again and Maddison rounded the desperate lunge of Edwards to score past Parish.
The scoreline will sting for the U's and they now go to Crewe looking to get back to winning ways.