Salzburg can still be targeted by Real Madrid for 3 important points that will help them maintain their automatic qualifying position. If they win over Salzburg, then Real Madrid's points will be 12 which will be able to maintain their survival even though they have to fight through the playoff zone.
In order to qualify for the next round even though there are two more matches left, I feel that they can qualify for the last 16 even though Brest is an opponent that can be considered tough considering their achievements during their six matches in the Champions League.
Real Madrid are only 3 points away from the top 8, and a win in two matches could change the table a lot, but on the other hand, those teams that are in the top also won't want to lose their positions. Maybe even if they can't get into the top 8, I have no doubt that they will make it to the playoffs. The difficulty will just be that they might get a tougher opponent in the early stages.
Real Madrid may be 3 points behind to take the top spot but the team that is at the top of the points table is already 3 points higher. If in the next match the number one team in the points table earns full points and Real Madrid earns the old points in the next match, there will still be a gap of 3 points between these two teams. Every season Real Madrid are more aggressive in Champions League matches but I didn't notice that this season especially at the beginning. Real Madrid have dropped points in several matches in the beginning so now they are failing to stay at the top of the points table. However, if Real Madrid cannot secure the second round from the top position, we can certainly expect that they will perform much better in the second round.