Even the winning they had was not easy despite that Benzema was not fit for the match. This second leg we all may witness surprising things, ofcourse it will not be surprising to see Real Madrid eliminate PSG. In this kind of case big names does not really count as the biggest name disappointed the last time and even missed pk.
I think that we all are forgetting something. After Messi has arrived in PSG, he doesn't look the same as before. He has lost his flair I would say. And age is also taking a toll. And Kylian Mbappé has a lot of transfer talks surrounding him. Now I am not saying that these things will affect the playstyle or results of the match but maybe this could cause some mental disadvantage for PSG.