I do not think that Real will have trouble at UCL until a point, but after that it is going to be tough. For example I am sure that they will be good enough in the UCL groups, that should be possible and they will get out of the group stages, it would be highly unlikely for them not to get out of the group stages, can't remember how many times that even happened. After that it all depends on the teams they match, because if they match with a big team right away then they may end up losing at last 16, but if they don't?
They can still beat people up until like semi finals based on lucky draw. They have enough of a good team to not be underrated against other teams, there are like maybe 3 teams on the whole world I would consider better than them.
With their current lineup, they have greater prospects of reaching the preliminary rounds of the UEFA Champions League. Carlo Ancelotti is an important figure in the club, an innovator who will go to every extent to ensure his squad wins crucial championships. Following the results of La Liga games, they are on a winning streak. I have no concerns about competing for titles because they are the greatest and most consistent at winning streaks. Real Madrid are in outstanding form this season, but the long run will be difficult for Los Blancos because they will face other elite opponents.
Last season's Real Madrid didn't do well in La Liga, spending too much time in the Champions League. So they won't make that mistake again in La Liga, they have a great chance to secure their title, their rivals are less here, so Real Madrid team is expected to do something amazing in La Liga this time.