Milan is a very unstable team and this season as in other seasons, they are performing very well and they won last game thanks to luck because Club Bregge got a red card early. I believe that if Club Bregge hadn't gotten a red card, then Milan wouldn't have won while Real Madrid is a very good team with a lot of experience in this competition and despite the defeat they had in the last La Liga game, they can easily beat Milan. Milan has a very bad defense and even if Real Madrid has an attack that wastes a lot of opportunities, they will still be able to score at least 2 goals and Real Madrid has a good defense.
Both have experience in UCL, despite Milan's poor performance lately, but Real Madrid still have to work hard if they want to win, I'm sure Milan can put up a tough fight later at the Bernabeu but still if it's to be favored Real Madrid must be chosen.
My prediction is that Milan can score at least one goal because Madrid's defense is shaky, many important players cannot be fielded due to injuries, this opens up opportunities for Milan and of course they have observed this.
In my opinion the final score is 2-1 or maybe 3-1 for Real Madrid's victory.