Two moments of misfortune cost the U's dear on Saturday as they fell to their first home defeat of the season against Doncaster Rovers.
At the start of the first half, a miscued Mark Cousins clearance was returned with interest by David Cotterill and, at the start of the second, Andy Bond nodded home an own goal past his helpless goalkeeper.
In between those two goals, the U's had responded well, testing Rovers and not only drawing level through Magnus Okuonghae, but smacking the bar with a Marcus Bean thunderbolt.
But having fallen behind again in the second half, they were unable to get themselves going a second time to muster anything from the game.
With results elsewhere going against them, the U's slipped to the foot of the League One table.
The U’s made two changes to their starting eleven, with Michael Rose coming in for Ben Coker, whilst Gavin Massey replaced the injured Anthony Wordsworth, who was fit enough to make it onto the substitutes’ bench.
The home side would have been looking for a solid start to the game but a mistake from Cousins saw the ball given straight to Cotterill, who returned the ball with interest as he smashed one home past the U’s keeper from the edge of the box.
Led by Cotterill’s early example, Brown picked the ball up just in front of his midfield and smashed in a shot of his own, but he had always dragged his effort and it went well wide.
Having started the game in the worst possible fashion, they got themselves back on their feet as the match approached the ten minute mark.
Bond tested Woods with a free kick on the ten minute mark, which the Doncaster keeper parried around the post for a corner.
The U’s were growing into the match without seriously testing Woods, although territorially, they were beginning to get on top.
They had their best chance of the game midway through the first half as a clever Henderson dummy set Sears away and he bore down on goal where, under pressure from McCombe, he forced a smart stop out of Woods.
The Col U pressure was growing and McCombe blocked another Sears effort, clipping the defender and going over the bar.
The home team had Rovers penned in, and they got the goal their efforts deserved on the half hour mark.
The ball was not fully cleared from a set piece and as it came to Okuonghae, his shot clipped the inside of the far post.
It looked like it might stay out but, despite the efforts of keeper Woods and his defenders, it snuck in and over the line.
The U’s almost got their noses in front seven minutes before the interval.
Another fine move down the left saw Massey cut in and the ball was moved across to Bean, who stabbed a side footed effort that crashed against the crossbar and clear.
Rovers were not out of it though and Brown should have done better shortly after that Bean effort as he looped an effort wide of the far post.
All of the U’s good work towards the end of the first half was undone shortly after the restart. A free kick was thrown into the box and Bond stretched to clear the ball but nodded it past Cousins to make it 2-1 to the visitors.
Eastman was in the right place at the right time to block Brown’s close range effort but the striker should have done better shortly afterwards when a ball across goal found him at the far post but he air kicked.
Henderson and Sears repeated their dummy routine to get Sears into the box, but his hopes of getting a shot away were denied by the outstretched leg of Jones.
From the corner, Massey set himself for the shot, but his effort was blocked behind for another set piece.
The former Watford man continued to be in the thick of it and drew warm applause from the crowd for another darting run that caused confusion in the visitors area with a fierce shot.
Syers missed a great chance for 3-1 as he ran into the area for a cut back to him 15 yards out, but he completely missed the ball with his kick and the U’s cleared the danger.
The U’s changed it around on the hour mark as they went 4-4-2 for the last half an hour, Sears joining Morrison up top and Henderson and Massey dropping to the wings.
Wilson went into the book for handling on the edge of the box midway through the second half, the resulting free kick clipping off the wall and going away to safety for a corner.
The U’s made their second change with seventeen minutes remaining as Wordsworth replaced Izzet for the last seventeen minutes.
As much as they prompted and probed, they found it hard to get the ball past the man mountain that was Rob Jones, who repelled everything heading his way.
Chances had become more restricted in the second half for the U’s, although Wordsworth poked one wide with five minutes left, which Woods was happy to watch go by.
Sears had a half shout for handball as he lashed a volley towards goal from Wordsworth’s free kick.
But that was as close as the U's got in those dying stages as the home team continued their search for their first win of the season.