Kevin Bru and David McGoldrick - from the penalty spot - twice gave the Blues the lead at Colchester but the U’s ran out 3-2 victors in the now-annual friendly at the Weston Homes Community Stadium. For the home side, Alex Gilbey scored twice and Gavin Massey a late, late winner.
Trialists Giles Coke and Larsen Touré started for the Blues with only Cole Skuse not making the trip due to a minor niggle.
Goalmouth action was rare in the opening spell and it wasn’t until the 13th minute that either side threatened, Bru picking up a loose ball midway inside the Colchester half and hitting a 25-yard effort which was too close to U’s keeper Elliot Parish.
Town, again in last season's orange away kit, came close to taking the lead in the 21st minute after a superb interchange of passes on the right. Pitman dummied, Ambrose then played the ball to the striker, who fed former Colchester man Sears, whose shot was blocked by Parish. The loose ball deflected out to Jonny Parr, but the Norwegian shot into the side-netting when he should have opened the scoring.
George Moncur shot wide for the home side, then on 23 skipper Chris Porter battled his way beyond Tommy Smith but the advancing Dean Gerken - also back at his old club - dived at his feet to block.
The U’s threatened again on 29, Moncur hitting a low shot from distance which Gerken could only parry. Porter was first to the rebound but couldn’t find the target as Smith closed down.
Just after the half hour trialist Touré, who had started wide on the right, made way for Dylan Connolly, the Guinean international having made one or two feisty challenges and a couple of strong runs, but had been caught in possession on a number of occasions.
On 36 Pitman looped a header over from a Coke freekick, then four minutes later Drey Wright, son of former Blue Jermaine Wright, shot over from distance.
The Blues took the lead right on the stroke of half-time. Ambrose, who is training with Town as he looks to win a new deal, exchanged passes with Sears on the left, the former Colchester man cut the ball back beyond Pitman but perfectly for Bru, who smashed a right-foot shot past Parish and into the net. The referee’s whistle blew moments after the restart.
Bru’s goal was very much the highlight of an evenly-contested, typical pre-season first half of few chances at either end.
At the start of the second half the Blues brought on Josh Emmanuel, Josh Yorwerth, Ryan Fraser, Teddy Bishop, David McGoldrick and Daryl Murphy for skipper Luke Chambers, Smith, Connolly, Bru, Sears and Pitman.
Alex Gilbey struck the first shot of the second half from distance, Gerken getting down to his right and claiming at the second attempt ahead of the on-rushing Porter.
Colchester got back on terms on 55 when Moncur made a strong run through the middle before laying the ball to Gilbey, who beat the advancing Gerken from midway inside the area on the left.
Ambrose hit a low volley not far wide before Myles Kenlock and Ainsley Maitland-Niles replaced Parr and Ambrose.
The Blues regained the lead from the penalty spot in the 65th minute. Emmanuel’s deep cross from the right was nodded down and across by Murphy to McGoldrick, whose powerful shot was stopped by Alex Wynter’s hand.
Referee Mr T Robinson pointed to the spot and McGoldrick sent Parish the wrong way to claim his second goal of pre-season.
The Blues came close to adding to their lead on 72 when Maitland-Niles threaded in Fraser on the left. The on-loan Bournemouth man crossed to Murphy, who just couldn’t get his header on target.
Bishop shot weakly through to Colchester’s sub keeper Sam Walker, before the game turned around in the final minutes.
Colchester got back on terms when Gilbey picked the ball up not far outside the area and hit a powerful low shot which beat Gerken.
Then, in the final minute of scheduled time, the U’s took the lead for the first time. Sub Dion Sembie-Ferris held off Berra before Jack Curtis whipped over a cross-shot beyond Gerken and Gavin Massey bundled the ball home behind him.
There was no time for the Blues to hit back and the League One side claimed a rare victory over their local rivals.
Until the late goals, the match had appeared to be drifting to a Town win, having somewhat lost its momentum after the traditional pre-season mass of substitutions.
But the U's showed admirable desire in the closing minutes to grab the win and send their fans - who were just outnumbered by the travelling Blues - away happy.
Colchester: Parish (Walker 70), Brindley, Wynter, Eastman (Curtis 80), Vincent-Young, Edwards, Gilbey, Moncur (Kent 80), Wright (Sembie-Ferris 56), Porter, Massey. Subs: Olufemi, Lapslie, Bonne, Holman.
Town: Gerken, Chambers (Emmanuel 46), Berra, Smith (Yorwerth 46), Parr (Kenlock 63), Coke (Tabb 72), Bru (Bishop 46), Touré (Connolly 31 (Fraser 46)), Ambrose (Maitland-Niles 63), Sears (McGoldrick 46), Pitman (Murphy 46). Subs: Crowe, McDonnell, Stewart, Henshall, Benyu. Att: 4,647 (Town: 2,372).