Barcelona just play in the best way that can lead them to victory. I think Barcelona already understand Real Madrid very well and the of playing that will be easy for them to defeat Real Madrid. So surprising that in as much Real Madrid played well and more impressive than Barcelona they still could not win the game. The defensive patter Barcelona used in the game was the reason of victory for them.
Almost all of real madrid's tactics can be read easily by xavi. It can from the decision already taken by xavi to give advice to its club for doing full defense against real madrid. i am aware how frustated real Madrid's players were when it was losing 1 goal due to its own goal. The second leg gonna be an even more difficult match for madrid. Ancellotti needs to think about another tactic and stop to use the same tactic against barcelona. Madrid will be losing in the second leg if ancellotti keeps using the same strategy against barcelona. Putting all of players to be fully in defensive mode was making madrid just like faced the big wall.
I don't think it was Ancelotti's tactical fault on the contrary, Real Madrid were able to control the ballposition more and play much better but they were just unlucky in the first leg of the Copa Del Rey against Barcelona.
and for the second leg later I think these two teams still have the same chance to beat each other, in fact I think the percentage of these two teams is still 50-50.
and it is true that since Xavi has coached Barcelona there have been very many positive changes that have occurred and especially in this season which has made Barcelona at the top of the La Liga standings temporarily.
Real Madrid didn't have a lot of solutions to the strong defense of Barcelona. And this is what Barcelona is counting on. They took the first difficult hurdle by collecting the three points and scoring a goal in Madrid. That is more than they expected. I am sure they would have been ok with a draw and then try to win it at home.
Now the situation is quite different and I think it is not a 50-50 game anymore. It is more like 58-42, probably not quite 60-40. Also, some of the players that were now missing in Madrid will return until the second leg if everything goes according to plan. That is Lewandowski, Pedri, but also Dembele as far as I know. That is a whole different story for their offensive game and another threat that Real Madrid has to take care of during the game while they need to try and play offensive themselves.