City overcame record 13-time winners Real 4-2 on aggregate to progress to the quarter-finals.
Sterling declared: "Energy, passion. It is a competition we want to do well in. If we play our football and run our socks off then the result will come.
"We know how good they are, we know how good we are and the difference was who would run the most and I thought we were brilliant today.
"We wanted to be right on them and from our pressing we got two goals. A great achievement (to score 100 goals for the club), hopefully plenty more to follow."