Manchester City will have to accept the defeat from Real Madrid because they know that they will never find it easy to stop the strikers of Real Madrid because we all know that Real Madrid has one of the strongest strikers this season, and we know that Manchester City's defence is weak, which you even mentioned. So that game will not be that easy for Manchester City because their performance is not in a good form, considering that Real Madrid is not a good match for them because Real Madrid's performance is not even comparable to Manchester City's performance this season. That is just the fact.
The match isn't over yet, why Man City must accept the defeat? 
Both teams performed worse than previous season, they are not in their best form. Both have strong attackers but they have a problem in the defense line. It is not only Man City which has weak defense, Real Madrid also has fragile defense because some of their main defenders are injured. They only can use the young defenders who have lack of experiences from Real Madrid Castilla. So, there is no big difference on the defense line. By the way, Real Madrid has better midfielders, they can use all the best players in this line. Meanwhile Man City still can't use Rodri because he is injured for a long time. But we don't know how they will play in the match. Sometimes the mentality of the players and the tactics can has a bigger role in the match.