At that time Atletico Madrid had to accept defeat to Atletico Bilbao with a thin score of 1-0. It was a painful defeat because they got at their own headquarters and even in the game Atletico Madrid actually played better than their guests, but luck was not on their side at that time. Atletico Bilbao's goal came from the spot in the first half, in the 25th minute.
In this match Atletico Madrid certainly want to avenge their defeat in the previous match, and they want to do it at home to Atletico Madrid. For Atletico Madrid themselves there is no other choice but they have to appear to attack because they have to equalize the score first. This is the second leg of the semi-final, so there is no reason for them to play it safe, unless they are already ahead.
Maybe that can be done by Atletico Bilbao, but it is also definitely at risk if they play safe and more defensive. Because if they continue to get tension then they must increase their concentration even higher, because in a decisive match like this, concentration becomes something very important, because once they lose concentration then the opponent will be able to create goals.