Earlier this month, UEFA announced that City had been banned from entering European competitions for two years due to a serious financial breach, putting the pressure on the club to break their Champions League duck this season.
Regardless of the stature of their opponents in the last 16, De Bruyne admits that City will receive criticism should they not see off the Spanish giants.
De Bruyne is quoted by The Mirror as saying: "If we don't win it, everybody is going to say we are failures like the last five years. It's something we've not won yet. We always want to win everything but sometimes another team is better or performing well – like Liverpool are doing this season.
"It's just that way and you just have to admit it, but we will just go there to win that game. You can't look too much forwards and see what's going to happen."
The first leg of the double-header takes place at the Bernabeu on Wednesday night.