Napoli and Barcelona may not be in their best form, but Napoli are no more experienced in the Champions League than Barcelona. I believe Xavi can get his team to play better from now on and win more games, but he has to be very careful against Napoli. After all, Napoli still have great players who can give Barcelona suffering until they fail to qualify for the quarter-finals.
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..