An own goal from Terrell Forbes was enough to give Colchester victory at Leyton Orient.
The hosts had an excellent early chance but Kevin Lisbie shot straight at keeper Ben Williams from close range.
Colchester took the lead when Karl Duguid's cross was turned in by Forbes under pressure from Ian Henderson.
The visitors missed a great chance to double their advantage when Gavin Massey rounded goalkeeper Lee Butcher but shot wide from 10 yards.
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Leyton Orient manager Russell Slade told BBC London 94.9:
"We started brightly enough. The first goal was going to be an important in a tight game and so it proved in the end.
"Colchester did defend well, but my concern is we need to create more chances and then when we do get in to areas we need to make more of the openings.
"We absolutely should have had a penalty. It is a penalty every day of the week. The referee does let things go and let the game go, that's his style, but he let a penalty go today.
"The own goal is unfortunate. It was their only real chance and it gave them something to hang onto."
Colchester United manager John Ward told BBC Essex:
"We've had a tough week with a bit of criticism and we needed a reaction, a positive one, and that's exactly what we've got.
"We had match-winners in the team and match-winners off the bench. People like Kayode (Odejayi), Andrew Bond and Steven Gillespie (were) itching to come on.
"I was really pleased with the little bit of juggling we did up front with Ian Henderson and Gavin Massey coming in and Karl Duguid working in there.
"We had good legs and good endeavour to try and get in behind and cause problems for Leyton Orient, and it came off so it was good."