Roberto Mancini's side had to grab a late win over Tottenham Hotspur on Sunday and they have not been at their best this season.
But City are facing opponents every week who are likely to raise the level of their performances due to the fact they are playing against the title holders.
And full-back Zabaleta knows it is going to be a tough campaign when critics will voice their opinions at every opportunity.
He said: "We have come a long way in the last four years and the expectations have changed.
"It's normal that when you win the title, people will knock you at the first opportunity.
"You are up there to be shot at and we take it all on the chin.
"It happens at other clubs. It's just the way things are."