Atletico Madrid is a tough opponent for any big club in Champions League but by understanding Real Madrid very well, they are one of most unwanted opponents with Real Madrid. Similarly Bayern Munich did not want to play with Bayer Leverkusen in Champions League too but destiny attracts them playing against each other.
It could be that Atletico Madrid will be a nightmare for Real Madrid even though we know that Real Madrid is not an ordinary team that is easily eliminated when they compete in the Champions League.
If Bayern Munich with Bayer Leverkusen, I think Bayern Munich can be relied on based on their history of appearing in the Champions League.