None of these teams are "much stronger" than the other. The score shouldn't absolutely mislead people. PSG were better in the first half but City developed a better strategy in the second half and took the advantage. I don't think that City's job will be easy in the second leg also.
Agreed,,, like I said, they each took a half and the scoreline does not really reflect it, it could very easily go the other way (just like how PSG were outplayed by Bayern Munich and yet still got the full victory). This is football and a small slice of luck is needed every now and then. City will be facing a big task they know it.