Real Madrid's opponent in the Super Sixteen is Atletico Madrid. Atletico Madrid as an opponent is not easy at all so Real Madrid must plan hard and then take the field against Atletico Madrid. Usually the competition between two teams from the same league is often less but this season we will see two of the best teams in La Liga Real Madrid and Atletico Madrid facing each other. The next two teams in the same group are PSV and Arsenal.
For now I think Arsenal will make the quarter finals from this group and Real Madrid will beat Atletico Madrid to make the quarter finals. And when these two teams go to the quarter finals, Arsenal and Real Madrid will again face each other in the quarter finals and there Real Madrid will secure the semi finals by defeating Arsenal. I have given this opinion only as per my personal prediction but the result may change.
Maybe every match in Super Sixteen can be much more important as Real Madrid will play against Atletico Madrid in Super Sixteen. A very strong football team that Atletico Madrid may have no doubt about this. They are also doing a lot of good performances in La Liga at present. In my opinion there is a much difficult match for PSG because they have to face Liverpool. Moreover, as you mentioned, I am not sure that Real Madrid will be defeated by Atletico Madrid in the quarterfinals. If the group you mentioned was very weak, it would have been reasonable to make such a predictions.