An own goal by Greg Taylor denied Cambridge a third straight league win following a 1-1 draw at Colchester at the JobServe Community Stadium.
Colchester came close to taking a fourth-minute lead through Omar Sowunmi, who was denied by goalkeeper Dimitar Mitov in the six-yard box following Harry Pell's flick-on.
Tommy Smith nodded just over from the resulting corner for the hosts and soon after striker Jevani Brown fired into the side-netting.
Cambridge took a 12th-minute lead somewhat against the run of play when Harvey Knibbs converted from close range, after keeper Dean Gerken had pushed away Paul Mullin's fierce cross-shot.
But Colchester levelled in the 39th minute when Callum Harriott drove in a shot that struck Cambridge defender Taylor and flew in after Cohen Bramall had driven down the left and crossed.
The second half was an even affair but Mitov made excellent saves to deny both Tom Eastman and Pell, while Mullin came agonisingly close late on for Cambridge as an entertaining contest finished all square.