But success in Europe has thus far evaded the star-studded squad within their dominance in England since Guardiola joined the club.
Now, with City being handed a two-year ban from Europe's elite club competition, pressure has arisen on the squad to win the crown for the first time in the club's history.
Ahead of the Round of 16 tie 13-time winners, Real, the Belgium international concedes, the failure label will be warranted if they exit at the hands of Zinedine Zidane's men.
"But I think we will go there to try to play our game like we always do and try to play offensive football, try to put them under pressure, try to have a good game and, if we can, win.
"If we don't win it [the Champions League] everybody is going to say we are failures like the last five years! It's something we've not won yet."
He added: "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."