The influential Ivorian has been out of sorts this term, and the former Barcelona star has hinted that the World Cup may be a factor behind his lethargy.
He told BBC Sport: "We know it is going to be tough this year. We won the Premier League last season but that is now in the past and we have to focus on improving and being more consistent.
"It's difficult because a lot of our important players have not had enough rest and recovery after the World Cup.
"As champions we want to win it again so we have to work hard because all the other teams are going to come at us and try to beat us. We need to deliver."
City host Premier League title rivals Chelsea on Sunday afternoon.