I hope they don't just rely on one player, in this case Victor Osimhen. I know he's been a very prolific player for Napoli's attacking line, but if Napoli have that dependency it won't be good for them. Now I hope that with or without Victor Osimhen, Napoli can play as usual without any problems that will cause them difficulties.
When the single player is someone as good as Osimhen, it is impossible to not rely on him to make the difference, I am not saying that is why they may get scored a lot, he wasn't a defender or a goalkeeper or even a midfielder, so they should be defending like nothing else happened and they should be fine about that.
But, when it comes to the fact that we are talking about a player that is scoring so many goals, it may become harder to score for them, not impossible because they can play others, but it would be still hard. Plus I am not sure how long he is out, maybe he will reach until the second leg at worst? That could be a good return for the team.