The Argentina striker says his winner against QPR still seems surreal.
"I did think it was all lost," Agüero told the New York Times. "But we had confidence and wanted to win. A friend said to me that we were too far from the top, but I always said it was possible with a lot of faith.
"When I scored the goal, I remember the euphoria. I took off my shirt and started running - where, I don't know. My teammates jumped on me, and when the game was finished, I couldn't believe it.
"I still don't think it has sunk in. It's weird. Only later did I start to realize how important it was to our fans. I don't think I realized that we had won the league until the next day. I was just in a different place, my own world."
He added: "Of course, when I first went to England, I did think it would be complicated. It's a different way of playing, and it was weird. But I thought I adapted well."