"I saw the replay in the dressing room", the five-time Ballon d'Or victor said of his eighth strike of the season.
"If we keep conceding goals before the opponent, there will arrive the day where we can not come back", he said.
'In a positive way is easy to feel a team that does not give up, always find a way to fight back sometimes changing results, sometimes not but we are a team that has that collective spirit to fight back but is not always possible.
However, Manchester United's defenders will need to be on their guard early as they have a worrying tendency to start poorly.
"I came here to do my job and I was insulted for 90 minutes", Mourinho said.
"I know English teams are always looking for set pieces. If his response is positive - and we have of course one more session tomorrow - he is ready".
Manchester City are sitting at the top of the Premier League table and nine points ahead of Manchester United, who are trailing the Citizens in eighth spot in the table. "We didn't have him in the first leg, Juventus introduced Barzagli to control us, but we immediately went direct and got the goals", Mourinho explained.
I was very pleased to score my first Champions League goal for Juventus, but we're in good shape.
"I was happy with the goal, but of course I'm a little bit disappointed because we should win the game with three or four goals".
"Even if the good results were not in our pockets, the performances were there".
"But what is behind I can not say but in this moment I have only to think about football, and to think about football is to think about Manchester City as a football team there".
Wednesday's 6-0 defeat of Shakhtar Donetsk underlined the quality of Sunday's opposition, but life off the field is not as rosy as City face allegations that they have tried to cheat European football's Financial Fair Play rules.