Defeat to Southend sends the U's out of Checkatrade Trophy.
The hosts put the U's under pressure from the first whistle, and had numerous chances to open the scoring before the first goal eventually came on thirty seven minutes.
A close range header from Josh Wright put the hosts ahead following Rene Gilmartin's save, before Theo Robinson doubled the lead a few minutes into the second half.
Boss John McGreal made nine changes to his starting eleven, but still fielded a side with plenty of first team experience.
Kane Vincent-Young was back in the line-up after injury, with fellow returnee Sammie Szmodics named on the U’s bench.
It was the hosts Southend that started the game on the front foot, with a dangerous ball to the far post being awkwardly cleared over his own bar by Sanmi Odelusi in the very first minute.
McLaughlin then had two chances to put his side ahead, but went wide with a volley and a free kick.
Those first three incidents in the U’s penalty area all came in the first ten minutes but the best chance then fell to McGlashen in the eleventh.
Leonard got in on the right after Lewis Kinsella failed to clear a cross, the ball was cleverly pulled back but McGlashan put his effort from twelve yards out well over the bar.
Josh Wright had the next opening for the Blues, but he followed McGlashan in hitting his falling volley over the U’s crossbar.
The U’s finally created a chance halfway through the first period, with Sanmi Odelusi finding strike partner Nicke Kabamba in behind the home defence.
The angle was too tight to shoot but the pull-back across the six yard box couldn’t find a U’s teammate and Turner was able to clear.
The play quickly returned to the other end, and Rene Gilmartin had to be alert to save with his feet from Ranger, after Robinson had miskicked in front of goal.
Leonard was the next Southend culprit, shooting wide on the stretch after Frankie Kent had touched on a whipped free kick into the U’s box on thirty four minutes.
Three minutes later, the hosts deservedly went ahead.
McLoughlin picked up the loose ball in midfield, moved forward and unleashed a shot from distance that Gilmartin could only parry straight to Wright, who headed calmly into the empty net.
Timlin, who was playing at left back for Southend, almost made it two but Gilmartin produced a stunning fingertip save to keep the score at 1-0.
Gilmartin then made a more regulation save from Robinson, who had sidestepped James before shooting straight at the U’s keeper.
The half time whistle went seconds later, and the U’s went in knowing that it could have been a lot worse than the one goal deficit.
One became two three minutes after the break though, with Robinson getting the goal his efforts deserved.
After combining with Ranger, the Southend forward went by Eastman before hitting a measured shot past the helpless Gilmartin and into the bottom corner.
The two goal cushion gave the hosts control of the game, and they comfortably protected their keeper Mark Oxley against any U’s threat.
They continued to threaten the U’s though, and Frankie Kent had to react quickly when the ball rebounded off him and went goalwards, clearing off the line with the assistant in a great position to see whether the ball had crossed the line or not.
Kent was putting his body on the line to prevent Southend increasing the lead, and the young defender denied Ranger on sixty six minutes with a vital block.
Former U’s defender John White almost got in on the goalscoring action, but having done the hard work in beating his marker, he shot straight at Gilmartin.
Sammie Szmodics had already replaced Cameron James at this stage, with little effect on the flow of the game, and McGreal decided other changes were needed as the game wore on.
Mikael Mandron and Brandon Hanlan replaced O’Sullivan and Slater but Oxley was still to have a shot to save as the game approached its final few minutes.
The game’s final chance went to the hosts, with the referee pointing to the penalty spot having judged Kent to have fouled his man as a corner was whipped in from the right side.
Sub Simon Cox had only been on the pitch a few minutes, but put the ball on the spot.
His powerfully struck shot hit the post and rebounded straight back to him – he hit the ball over the bar with his second attempt, but it would have been disallowed had he hit the target, as no other player had touched the ball before he hit the rebound.
It was the final action of the game, with the U’s beaten by a team that looked a division above them on the night.