City threw away a two-goal lead on their first visit to the Weston Homes Community Stadium as Colchester United struck twice in the space of seven second-half minutes to claim an unlikely point.
The Robins seemed on course for a routine victory after early goals in each half from Martin Paterson and Scott Wagstaff, with their hosts virtually non-existent as an attacking force.
But the defensive vulnerability which has blighted City’s season was exposed as Gavin Massey pulled one back before Freddie Sears hammered in the equaliser 11 minutes from time.
Steve Cotterill made one change to his side held to a goalless draw by ten-man Swindon Town at Ashton Gate last time out, with Paterson handed his first start since joining on loan from Huddersfield Town.
The Northern Irish international replaced Greg Cunningham as the Robins switched to a 4-3-3 formation, while Bristolian duo Joe Bryan and Bobby Reid were deemed not fit enough for a place in the squad – both through knee injuries.
City were straight on the front foot against a team their equal in terms of both points and goal difference at kick-off, with Jay Emmanuel-Thomas looking lively on the right of a front three.
First he tried his luck from distance after the ball sat up kindly, seeing his dipping shot bounce awkwardly in front of former Bristol Rovers keeper Sam Walker, who awkwardly shovelled the ball behind for a corner.
It was a typically powerful burst of acceleration from Emmanuel-Thomas which paved the way for City’s opener.
Driving between two defenders, the enigmatic frontman pulled the ball back for the onrushing Sam Baldock, who was only denied by a last-ditch intervention before Paterson gobbled up the loose ball with a simple finish.
It was not the end of the visitors’ fast start, as Derrick Williams’ cross from the right reached Emmanuel-Thomas unmarked, but he could only flick a hopeful toe at the bouncing ball and attempt to lob the imposing Walker only for his effort to clear the crossbar.
Eventually the home team did rally, as Alex Gilbey scuffed one wide before the same player forced Frank Fielding into a fine save diving to his left after the City stopper had unconvincingly punched clear an inswinging free kick.
Former Arsenal colleagues Sanchez Watt and Emmanuel-Thomas exchanged miss-hit attempts at goal easily dealt with before Baldock sharply latched on to a Williams ball over the top and connected sweetly on his left foot but his shot was straight at Walker.
City were well worth their lead and should have doubled the advantage shortly before half-time. Brendan Moloney’s surge from right-back carried him deep into Colchester territory, before Baldock slipped the ball through for Emmanuel-Thomas.
You would have got long odds on the striker missing the target completely on his favoured left side, but, in trying to pick out the far corner, City’s number ten shanked the chance well wide.
The second half was to continue in a similar vein as City remained fully in control, helped by Wagstaff’s untidy finish for his first goal since returning from a five-week absence.
More good work from Moloney down the right initiated the opening, as the defender found a low cross which Baldock attempted to backflick goalwards only to mistime it.
When the loose ball fell the way of Wagstaff on the six-yard line, the midfielder’s shot took a looping deflection up into the air and dropped fortuitously into the net behind the beaten Walker.
The impressive Moloney had the ball in the net himself just past the hour, rifling home from Emmanuel-Thomas’ pass only for the offside flag to deny him a first league goal in City colours.
At the other end, substitute Sears tried his luck with a dipping volley the backpedalling Fielding did well to help on its way over.
That chance out of nothing prompted the best spell of the game for the U’s, although Cotterill’s side looked comfortable defensively until Massey pounced to pull a goal back 17 minutes from time.
Jabo Ibehre’s pass down the right side of the box released Marcus Bean, who produced a low ball across the six-yard box for Massey to convert from close range and give his team hope of an unlikely comeback.
Sure enough an equalising goal was imminent as Sears took aim and fired a low shot inside the near post from 25 yards to stun the visitors.
Colchester could not believe their luck and visibly retreated, seemingly satisfied with their point, and invited late City pressure.
But a series of Emmanuel-Thomas long throws were well defended and the introduction of Wes Burns proved too late to carve out a chance.
United replacement Macauley Bonne saw a header flash inches wide in the dying seconds in the closest either side came to snatching maximum points from a game City should have had wrapped up long before the drama arrived.