Currently both of them are not in their best performance, we can say that both Barcelona and Napoli are experiencing a little difficulty in optimizing their performance. However, fortunately, Barcelona has a coach who is actually quite solid at Barcelona, while Napoli is still in its early days with Mazzarri. So maybe Barcelona should have a better chance. But, Napoli also have great players, so this will be interesting..
These two teams both won their respective league championships last season but now both teams are not performing well, of course this will be an interesting match.
But for me what is interesting about these two teams is Batcelona because this is a big test to show how ready Barcelona is to compete in the best club competition. This is a weak Napoli team compared to last season, If barcelona can't overcome it, this is a big sign that Xavi may not be the coach who can take Barcelona forward.
When Xavi first came to the club, the team's week to week performance was spectacular, but now it is very poor. As a coach, over time you want to improve, not the other way around, where you start off good and then go bad.