Thomas Frank praised Colchester after they pushed Brentford all the way before the Premier League side sealed a 2-0 win to progress to the Carabao Cup third round.
The Bees took a 39th-minute lead when Keane Lewis-Potter finished calmly from close range, after being found by Shandon Baptiste in the area.
The visitors sealed victory in the first minute of stoppage time when Ivan Toney’s header from Saman Ghoddos’ corner struck Mads Bech Sorensen and flew in.
Bees boss Frank, who made 11 changes, said: “It was very hard, no doubt about that.
“Even though we changed a lot of players, I think we put a performance out there – the attitude, the concentration, the mindset is strong.
“Touch wood, we haven’t had any slip-ups against opponents that are lower in in the leagues than us and I’m very proud and pleased for that.
“I want to praise Colchester, because I thought they put up a brilliant fight. I think they made it difficult for us, especially the first 30.
“Then we scored a brilliant goal and were a little bit on top of the game in the second half but couldn’t score.
“But then they came in the game, invested more in long balls and (were) more direct…and we struggled.
“You can never be sure and they had a chance and Thomas (goalkeeper, Strakosha) made a good save. But we did a good job and we got a deserved win.”
Colchester boss Wayne Brown was pleased with the plucky display from his Sky Bet League Two team.
Brown said: “Brentford fully deserved their victory and I wish them all the best in the next round.
“The higher you go, the better teams you play against and the better the individuals – they are at the top of their game for a reason.
“They’ve got the cutting edge and that’s not me highlighting any of our individuals but ultimately, the chances that you create you have to put away.
“They’re vital periods of the game and you find yourselves 1-0 down after a slip and the lads could have easily thought ‘we’re 1-0 down against a Premier League outfit, it’s only going to go one way’ – but they didn’t.
“They kept on the front foot, they kept final third entries, we kept putting balls into good areas and we were a constant threat.
“I’m sure if you asked their back-four if they’ve been a game tonight, the answer would be ‘yes’.”
