Hoping that Atletico will be able to turn things around, nothing is impossible, Atletico only needs two goals from the results of the match because that is far enough for Atletico to advance to the next round, plus Atletico will play at home with supporters who will come tonight at least. could be a strength for Atletico Madrid in facing Inter Milan in the second leg.
I consider the strength of a team base on the previous matches, if you take a look with Atletico Madrid's results, they have a terrible record. It's completely different with Inter, they perform very well recently.
In terms of quality, both of them are similar, but their recent performance are the key to evaluate which one is good and which one is bad.
So, it's really hard to imagine Atletico Madrid will pull an upsets.