Tommy Smith’s first-half header secured Colchester their first away victory of the season in a 1-0 success at Scunthorpe.
The skipper was left unmarked in the 26th minute to nod home from an inviting Cohen Bramall cross.
The goal was the only real chance the U’s created – with goalkeeper Dean Gerken their man of the match for a string of fine stops which frustrated the hosts.
Gerken saved with his feet to keep out a low drive from Harrison McGahey from a well-worked Iron corner routine and then beat away a curling effort from Alfie Beestin on the stroke of half-time.
Scunthorpe piled on the pressure after the break, and were left to rue a manic seven minutes when they somehow failed to level.
Devarn Green was first denied by a post with a great hit from range and substitute Ryan Loft, moments after he saw a header which was ruled not to have crossed the line after bouncing down off the underside of the bar, had a powerful effort pushed away at full stretch by a flying Gerken.
The Iron continued to see plenty of possession in the final third, but the U’s dug in and held on.