Remember when UEFA changed their seeding rules a few months ago? Well, Real Madrid will not be a top seed club in next year's edition of the UEFA Champions League because of those new rules. The clubs who conquered the top 8 European league titles will be in the first pot during the draw, and those are: Barça, Chelsea, Bayern, Juventus, Benfica, PSG, Zenit and PSV.
This means that Real Madrid will be in the second pot facing one out of those 8 teams. Teams from the same country cannot play each other in the Group Stage, so scratch Barcelona from that list. Still, it would be extremely difficult for Real Madrid to play against teams like Chelsea or Bayern this early in the competition, as those matches could also affect the run at the Liga BBVA title.
Next year, Real Madrid should try to win La Liga in order to avoid such circumstance.