If it were possible they would have given Barcelona the laliga tittle yesterday because there performance this season prove that Barcelona will be crown the Spanish laliga champion before the end of the season.
I would say Ancelotti and Real Madrid were overconfident in this match. And I think that was one of the reasons for Real Madrid's defeat. One should never be overconfident. At least a team as strong as Barcelona should never be taken lightly.
There is no doubt that we saw excellent performances from both teams in the first half. Madrid's players were able to launch several powerful attacks. But Hansi Flick and Barcelona's offside tactics fell into the trap of Real Madrid players. And that's why Madrid fell behind. After scoring two goals, the goal was disallowed.
After Lewandowski scored in the second half I never saw Real Madrid players perform well. In the last 20 minutes of the match, we only saw the dominance of the Barcelona players. Madrid's players may have lost sight of their target. I would say Barcelona won because of Hansi Flick's excellent match strategy.
That being said, it was a shocking defeat for Real Madrid, nobody had anticipated this kind of disgraceful defeat. Everyone's mind was Real Madrid or Barcelona would win against each other but it will be a score not more than two goals