Yes Napoli has just beaten Milan in an away game so that is a real calibre Barcelona will be dealing with. Playing against Barcelona in the Europa League, you really have nothing to lose. All the pressure is on Barcelona. If they want to save the season in the slightest, the only chance they have is to win this title.
And I think that this season, it's Barcelona that needs a good result in the Europa League, otherwise they will have one of the worst times in their history.
In Spain, they are not even in a position to allow access to European competitions. Of course that will change for sure, but things are a bit complicated.