The U's have lost 1-0 at Crawley in the Checkatrade Trophy in the first of their group games.
A Collins header opened the scoring in the first half, finding the bottom corner from a Banton cross.
Despite the U's having the better of things in the second period, they couldn't force an equaliser and the hosts won by the single goal.
Before either side had created a chance, Sammie Szmodics pulled up and was feeling the top of his hamstring as he walked back into position.
John McGreal made five changes to his starting line-up, bringing in Vincent-Young, Wynter, Johnstone, Bonne and Sembie-Ferris.
He soon ran it off but was a bystander as the first effort came against the U’s with James Collins’ header being saved by Sam Walker down to his right.
The U’s keeper should have been tested further on seven minutes, but Josh Yorwerth took too long to get a shot away and Tom Eastman was able to block.
A good move involving Szmodics, Drey Wright, Macauley Bonne and Luke Kinsella ended in Bonne drilling his shot just over the crossbar on sixteen minutes.
A minute later, Szmodics repeated the feat but with a firm curler rather than a straight strike.
Jason Banton then had two chances in quick succession, first shooting straight at Walker and then hitting the inside of the post with a shot from the angle.
Denny Johnstone looked poised to head goalwards on twenty seven but Connelly just touched it past the U’s striker.
Walker was back in the action at the other end on the half hour mark, comfortably saving from Connelly who had ventured forward from his centre half position.
On thirty three minutes, the hosts took the lead and it was a some good movement that made it 1-0.
The U’s were moved towards the ball on their left hand side, leaving Collins on his own at the far post to head home across Walker into the bottom corner.
The U’s tried to get straight back into the game and Johnstone thought he might get the equaliser when he rounded the keeper after being found by Szmodics.
Unfortunately, a defender had made the ground behind is keeper and was able to clear the shot Johnstone tried.
As the game went into injury time at the end of the first half, Wright tried his luck with a curler but didn’t get the swerve he wanted and it whistled past the far post.
That was the final chance of the first period and the teams trooped off with the hosts leading 1-0.
The second half started with the U’s looking to get back in the game, with Bonne deflecting a Szmodics shot wide in the fifty third minute.
Wright then hit a free kick from thirty five yards, which the home keeper nearly let slip through his legs.
The best chance of the half came when Johnstone won possession wide, cut inside and unleashed a right foot shot towards the top corner.
Beeney superbly tipped it onto the bar and over though to preserve Crawley’s lead.
Diaz Wright and Dexter Peter made their U’s debut as substitutes for Lapslie and Szmodics as the U’s went in search of a late leveller.
Bonne’s near post header went well wide and then Eastman’s shot was bundled wide, before Johnstone’s effort also missed the target.
The U’s lost this game in the Checkatrade Trophy but they can still go through with positive results against Charlton and Southampton in the group stage.