Manchester City under Pep Guardiola have been one of the most consistent clubs in the UEFA Champions League in the past five years so I don't think anyone who understands the game of football would want to underestimate their abilities just because they're having a bad season. Real Madrid on the other side is the defending champions in the UEFA Champions League competition but apart from being the reigning champions, they've easily been a better team than Manchester City since the start of the current season.
The play-off tie between these two European champions is actually a difficult one to predict but because Real Madrid's current run of form and the quality of players at their disposal, a lot of people are of the opinion that they'll easily get the better of Manchester City and progress to the next round of the competition and I think I totally agree to that