COLCHESTER centre-back Liam Chilvers put the boot into Town's League I play-off hopes with an injury-time equaliser.
It had seemed that despite a disappointing display, Peter Jackson's side, with a controversial 24th goal of the season by Pawel Abbott and a sizzling Danny Schofield strike, were on course for the sixth straight win which would have kept alive their albeit slim chance of a top-six finish.
But Colchester, who to their credit put up a spirited performance even though they had nothing other than pride to play for, had other ideas.
Having lost both centre-backs, brothers Nathan and Tom Clarke, through injury, Town were already looking nervy.
And when referee Andy Woolmer signalled five minutes of additional time, Colchester seemed visibly lifted.
Pushing forward with real purpose against a back four which by now included striker Andy Booth as an emergency measure, Neil Danns fired in a shot which deflected off Adnan Ahmed for a corner.
Danns' fellow midfielder Kevin Watson flighted in a flag kick which goalkeeper Paul Rachubka should have collected but didn't, and the lurking Chilvers bundled the ball home.
There was still time for a penalty area scramble in which Abbott came close to forcing a winner, but 14th-placed Colchester deservedly stretched their unbeaten run to eight games.
The Essex side had started the brighter of the two teams, restricting Town to just one effort on goal - a looping angled shot by Booth from right-back David Mirfin's pass which went over the top - before they made the breakthrough their pressure promised in the 19th minute.
Watson gained possesion 30 yards out and threaded the ball through to right-sided midfielder Richard Garcia.
He wrongfooted Town left-back Danny Adams to surge into the box and fire over a cross which Rachubka could only palm into the path of Danns, whose shot flew between Tom Clarke and Ahmed and into the net.
But Town were behind for less than 90 seconds - thanks to Abbott's quick thinking and accurate right foot.
Having been fouled by Chilvers as he advanced towards the area, Abbott got back to his feet and, seeing that goalkeeper Aidan Davison was still arranging his wall and out of position, curled the ball into the former Bradford stopper's right-hand corner.
It was an effort reminiscent of Thierry Henry's strike for Arsenal against Chelsea at Higbury back in December, and Colchester were just as angry as John Terry and Co had been.
Whistler Woolmer, however, was happy, and Town were level.
Colchester had the better chances in the remainder of the first half, with Rachubka holding a low shot by striker Marino Keith, Watson shooting wide from a good position, and Keith firing over after a Watson effort had been blocked by Nathan Clarke.
Town had fashioned few chances, but made the most of the one that came their way in the 62nd minute.
Abbott provided a neat cross from the right, Booth rose to head the ball on and Schofield, in plenty of space, made no mistake with a sweet shot which gave Davison no chance.
Town were disrupted six minutes later when Tom Clarke, having had an excellent game, was forced off with a hamstring strain sustained while sliding in to tackle Keith.
Abbott came close to stretching the lead with a 79th-minute shot which Davison held low down before Nathan Clarke was sidelined after 86 minutes with a gashed lip sustained in an aerial meeting with Keith.
There was a nervous moment on 88 when striker Greg Halford headed over, then misery when Chilvers pounced.
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MAN OF THE MATCH: Tom Clarke
THE teenager was outstanding in the centre of defence and had he and brother Nathan not been forced off through hamstring and facial injuries respectively, Town would probably have held out to win.
HOW THEY RATED:
Paul Rachubka Arguably at fault for both Colchester goals, certainly the second, and will want to forget this match. Rating: 5/10.
David Mirfin Did little wrong at either right-back or centre-back, where he moved when Tom Clarke went off with his hamstring problem. Rating: 7/10.
Nathan Clarke Another confident display and formed a fine partnership with his younger brother. His injury was a blow. Rating: 8/10.
Tom Clarke A top-class show against awkward opponents in Halford and Keith. Hopefully he'll recover quickly. Rating:7/10.
Danny Adams A mixed afternoon. Caught out for Colchester's first but also made some telling interventions Rating: 6/10.
Chris Brandon Workrate was excellent and his battle with Gavin Johnson provided an interesting sub-plot. Rating:7/10.
Lee Fowler Big chance in Jon Worthington's absence, but a disappointing display. For every good ball, played a bad one. Rating: 6/10.
Adnan Ahmed Full of running and wasn't scared of getting stuck in as he celebrated his new two-year contract with Town. Rating:7/10.
Danny Schofield Put his goal away with power and accuracy, but otherwise had a pretty quiet afternoon out on the left. Rating: 7/10.
Andy Booth A willing worker whose neat flicked header set up Schofield's goal. Stood in at centre-back in the closing stages. Rating: 7/10.
Pawel Abbott Showed great awareness to fire home the free-kick which put Town level and set up the second goal too. Rating: 7/10.
TURNING POINT: THE 68th-minute departure of Tom Clarke through injury.
The talented teenager suffered the hamstring strain in making yet another fine tackle, this time on Marino Keith, and with both Clarkes playing well in the centre of defence, Town looked more than capable of holding out.
Even with Nathan still on the field, they might have done so, but they also lost him.
SPOTLIGHT ON THE REF: DID little to endear himself to Colchester, who argued to a man that Pawel Abbott's free-kick was taken too quickly, but Andy Woolmer showed no hesitation in awarding the goal.
Kept control, and kept bookings to a minimum, with only Colchester duo Halford (dissent) carded.
Lost his assistant Alan Parker with a pulled muscle in stoppage time. Fourth official Tony McGee took over.
COLCHESTER UNITED: 4-4-2: Davison, Stockley (Williams, 83mins), Baldwin, Chilvers, White (Goodfellow, 72), Garcia (Jarvis, 72), Danns, Watson, Johnson, Halford, Keith. Subs not used: Elokobi, Gerken (gkp).