In general, Real Madrid is still able to survive in the UCL because luck is often on their side, including when facing Atletico in the second leg. At first I thought Madrid would be slaughtered after Atletico took the lead in the 1st minute, but after that Atletico were unable to increase their lead even though they always built fast attacks that troubled Madrid's defenders. There is no doubt about the mentality of Real Madrid players, but they still have 4 games left before reaching the final.
In the Champions League, Real Madrid, in addition to luck, also has the support of the referee, because this team often plays as champions, so in some controversial issues they get an advantage, even as it was in the cancelled penalty of Alvarez, in my opinion it is stupid to cancel such a penalty... So in order to beat Real Madrid, you need to be not only stronger than them. You also need to take into account other circumstances that can affect the result and in the case of Real Madrid, it is not only luck.
Referee support? are you saying that there is someone who plays unfairly in the champions league and deliberately makes Real Madrid given luxury? of course you have to explain why it is assumed for the Real Madrid match, if the cancellation of the penalty is based on the rules of course it is not cheating right? the referee just wants to enforce the rules that the league has given him to enforce, and yes there is no problem between the two parties, if it is a violation then I think the management of Atletico Madrid is not stupid either, they will definitely report it.