The City midfielder struck in the Carling Cup victory over Birmingham City.
Hargreaves was taken off shortly before the hour in a pre-planned move by City boss Roberto Mancini, and he admits he is delighted to be playing again.
"I knew I wasn't far away, just a few tweaks - every time," he told City's official website.
"I don't think people would believe me if I said everything that went on, but I am just happy to be back as I never anticipated in my life I would be out for three years - but I am back and I am happy.
"I think there was a misconception, I just needed to get in the right direction and the staff and everyone has done well, it will just take time to get into the tempo but so far it has been a great."
Hargreaves revealed he played in a behind closed doors game last week, so there was little doubt he was ready to feature.
"It feels good to get the first game out of the way, but we had a training game last week and I played for an hour - but this was the first official one," he said.
"The lads did well, professional and to get a couple of early goals helped and all in all it was a decent performance.
"I don't score a ton, because I am a midfielder but when I do score they are normally from distance, I don't get many but they tend to be good."