After securing the U's first league win of the season against Northampton, boss John McGreal couldn’t have been happier with his side.
A second-half penalty from club top scorer Luke Norris was enough for Colchester United to see off the Cobblers.
"I’m delighted with it. I thought we probably deserved it as well. I thought lately in some games we haven't been able to get the rub of the green. However, we got it today and we earnt it. Their goalkeeper made some fantastic saves," he said.
"It's a hot day and you want to try and change things. I felt we needed an injection with Gambs," the boss said.
"He’s been very effective from the bench. Ten minutes into the second-half I believed we could win the game. That’s the idea of putting someone on to try and force the issue and he definitely did that for us," he added.
"It's a well-deserved three points."
Super sub Gambin was also relieved his side ground out victory to earn a first clean sheet of the season.
"I was happy to get on the pitch. I thought the team did well to get the win. That’s good for us and the confidence of the squad. That was the most important thing," the midfielder said after the match.
"We had a little spell about 20 minutes after the goal where we felt under pressure a bit but we dealt with it well. I'm just happy we got three points."
Next up for the U's is Tuesday’s crunch Carabao Cup clash against Premier League Crystal Palace and the gaffer opened up on his excitement at taking on the Eagles.
"We go there Tuesday. It's a great game for us. It's the first time in 10 years we’ve got to the Second Round so we’ll go there and try to enjoy it," he said.
Gambin's performance may well have launched him into his manager's starting line up for Tuesday's Carabao Cup encounter and he appears keen to take that chance.
"It would be nice for the lads to go there and play at Selhurst Park. We'll give our all for the fans. I'm very excited. Every player wants to play on nice pitches against the best players."