Anthony Wordsworth scored the only goal of the game as Colchester beat 10-man Walsall at home.
Wordsworth gave the U's the lead from the penalty spot after Michail Antonio was brought down in the box by Andy Butler, who was subsequently sent off.
The Saddlers had a penalty claim turned down when Colchester's Magnus Okuonghae appeared to handle inside the area.
Kayode Odejayi then had a late chance to put the game beyond doubt but was denied by Walsall keeper Jimmy Walker.
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Colchester manager John Ward told BBC Essex:
"We said at half time if we can get three or four we would try and do that, we will try and increase the lead.
"But the important fact as well is that you don't lose it, and we've really negated the shooting opportunities of Walsall.
"they've been very well organised, we've created one or two things and found Jimmy Walker in good form."