Barcelona will definitely beat Napoli, Walter Mazzari is not even the man for Napoli, this are just try and error coaches, for long term, you need a better and tactical genius for that club.
the situation might be different when Napoli's performance is like last season, with the same players and coach. but the situation is different, Xavi and the Barcelona squad will be more favored to win in advancing to the next round.
The tightest competition is probably Inter's match against Atletico Madrid. and there is a possibility that the last 8 rounds will bring together strong European teams who are favorites in the Champions League.
I'm not placing any wager because I'm not confident of these clubs, we have become acquainted with the football system and we know how these clubs slack behind the require expectations in matches. Napoli performance last season is entirely different from the present, watching them winning the scudetto and also watching Barcelona winning the La Liga title and this season, both clubs having poor performance and stats in matches played. Xavi Hernandez and Walter Mazzarri meets and we will contemplate on the side that will be awarded three points. We don't underrate both sides simply because both teams fluctuates in performance and they will be facing each other in the round of 16.