It looks like this will be a deciding match for both of them because whoever loses this match will have a tough time qualifying for the playoffs. They don't just have to win the last game, but they will also likely depend on the matches of other teams. If you look at the current situation, PSG might have a better chance of winning than Man City because they have the home advantage and Man City has been really bad recently. Luckily the match will still be held for quite some time, so Man City still has time to improve their performance, and they might take advantage of this January transfer window.
Having this game as a deciding game for both teams has to be one reason why this game is going to be really tough and possibly interesting because both teams will be aiming to win but then win and they cant win together as one team has gat to win as against the other, Manchester City has been of a very poor performance and we all know but i still wouldn't use that as a reason to think that PSG was going to be the winner in this game, the most likely score I'm even expecting from PSG would be a draw and a win possible Win for Manchester City, Pep has always got his way around games like this and i don't see him loosing this particular one.