Well, in the round of 16, matches often end in surprises. We have to remember last season's round of 16. At that time, the favorite team stopped in the round of 16. And maybe this time the same thing will happen. But for the Arsenal vs Porto match, maybe I will still have confidence that Arsenal will be the winner and qualify for the next stage. But for the Barcelona vs Napoli match, I think this one is more difficult for us to predict. Even Barcelona is not as good as we think at the moment. Lewandowski even seems to have lost his sharpness this season. This 35 year old man even had difficulty scoring goals this season. So I also prefer to think that the Barcelona vs Napoli match has a 50:50 chance. Because anything can still happen. Napoli also seems to be trying to focus more on Serie A and the Champions League because they have been eliminated from the Coppa Italia.
maybe I have a slightly different opinion from you, Arsenal vs Porto, I predict that Arsenal can get past Porto and move on to the next match and for Barcelona I actually doubt that Barcelona can't beat Napoli because in the transfer market Barcelona will still be a little confused about whether to keep Felix or not. on the one hand, the financial crisis experienced by Barcelona will not be able to keep Felix, while selling Lewandowski to a saudi arabian team makes more sense to get money, but Lewandowski refuses to go to saudi arabia.
so Barcelona finances are what makes performance doubtful because the new players who will be recruited are still unclear.
different from Arsenal which has better finances and can get the talented players they want and bringing in new talented players gives quite a good increase in performance and it seems like my reasons make sense to me and as you said often the round of 16 brings surprises and surprises will come from Barcelona who may not qualify.