Real Madrid must be able to overcome Salzburg first at the Santiago Bernabeu before playing away to Brest. It makes sense, although this is just a personal opinion, but I think Brest was very lucky in the last few games because they got slightly weaker opponents.
This match is very important for Real Madrid to determine their fate in the UCL, so they will play with high spirits to maintain their chances of qualifying through the Play-offs.
The Santiago Bernabeu is a atmospheric ground where Real Madrid dominate and thrash oppositions, they don't welcome threat and easily defeats oppositions. We have weaker teams in UEFA Champions league and soon enough, they will eliminated from UCL. There are main elite teams in the UCL and competitive race is really tough. This is not supposed to be a debate for Real Madrid because we're acquainted with the historic records of Los Blancos, they're enchanced with potentials and winning games is necessary. Carlo Ancelotti knows what to do and comprehending matches is no difficulty for him, he's experienced and capable of hitting tougher goals with his team.
The match against Salzburg is not really something I did be worried Real Madrid will fumbled on especially now that Kylian Mbappe is getting rhyme back, while the injuries setbacks has been less severe as before.
Real Madrid defeated Atalanta who I think is more difficult than Salzburg, while they have been inconsistent before especially in the Champions League this season, this game will be better and they will end up victorious.
Real Madrid winning Salzburg is just a work over for them I really don't see it as a big match, kylian mbappe is now performing very well surely real Madrid will win Salzburg very well, however we all know that there last game real Madrid won with just 1 goal they where difficult for real Madrid so real Madrid needs to perform more and since real Madrid is still very inform more than before they will win for now real Madrid is still very much inform more than Salzburg.
Real Madrid Don't joke with champions League so they will play very well in other for them to win and qualify.