Maybe Real Madrid will not care much about the upcoming El Classico because they have a match against Bayern Munich and they already have good position and points on the table, so why to rush and risk against Barcelona? Barcelona has nothing to lose while Real Madrid might be in trouble if Barca plays tough and RM's players get injured. They want to preserve their players for the match against Bayern, Champion's League is very important for them and their points in La League give them a good advantage and excuse to even lose 1 match or end up with draw.
Real Madrid have now reached the semi-finals of the Champions League and of course Bayern Munich will be a difficult opponent for them later, but when you say Madrid no longer care about the game against Barcelona, obviously you are very wrong man, because againts barcelona very important for Ancelotti to be able to grab the two remaining trophies for Madrid this season. Throughout the season Madrid have been fighting to reach the top of La Liga, then when they are only one step away from winning the La Liga trophy why do you think they will let it go this season?
If you look at the current La Liga standings, of course you know how important the match against Barcelona is this week, currently Madrid is at the top of the standings and they are only 8 points separated from Barcelona in the second rank, so inevitably Madrid must take the match very seriously so that at least they are no longer chased in the remaining matches, I think for now Ancelotti will not underestimate Barcelona in order to give Madrid two trophies this season.