Yes, I think this is the first defeat for Madrid at the start of this season, so far they are playing on a winning streak and of course losing this Derby match is certainly not a failure for Madrid, because there is still a lot of time to catch up to win the Laliga title this season. This and even this defeat only made a difference of one point with Barcelona and Girona.
Atletico Madrid seems to know better how to beat Madrid at home, of course they have a lot of experience from each previous meeting, Madrid must recognize Atletico's greatness at home so this defeat must be an important lesson for Madrid so they can play better in the next match against Las Palmas , at least maintaining a safe position in the top 4 of the standings.
Ancelotti step of blaming himself in preparing the formation for the starting XI was the right step, this is part of his responsibility as a coach to protect the players mentality. Vinicius absence was felt when they met Atletico Madrid in the derby, Real Madrid front line became helpless and lost their creativity. Barcelona is now temporarily leading the standings, one point different from Madrid in third place. Girona is impressive by sitting in second place, they are unbeaten in six matches and have the same points as Barcelona.
However, I am optimistic for Real Madrid this season, when the players in the squad are available again, Ancelotti can maximize his potential to compete with big clubs in the next match. On the other hand, Diego Simeone does have a good record when meeting Ancelotti, his squad managed to hand Madrid their first defeat in this season campaign. Madrid can handle the follow-up match against Las Palmas easily, Vinicius looks like he can play in that match.