I'm not much positive about Barcelona's chance to eliminate Napoli honestly. Because their game is just not good enough. I believe that they haven't faced a real challenge yet. Porto were the second strongest team in the group but Barcelona won against them twice anyway. But I think Napoli are a bigger challenge than Porto for them.
Napoli have a stronger squad in the first place. They have a very dangerous player like Osimhen in their offense line. They are just trying to improve their form lately. But until this matchup I think Napoli will be in a better shape than now. If Barcelona don't make improvement at the same time then they can really say goodbye to the CL early.
Barcelona qualified from the group stage, in my opinion, because they were in an easy group with weak teams. Porto, who I thought would be tough for them, Barcelona defeated them in their two group stage meeting. In football, anything can happen, but all I can predict for Barcelona's next champions league their game against Napoli is that they will lose because Napoli is stronger than them even though they aren't playing well like last season With their poor performance, Barcelona will never be able to qualify through the round of 16, if they are in the same group as PSG and Dortmund, since in the group stage Barcelona have being eliminate from Champions league.
To be honest, this is the only match in the Uefa Champions League which will be a 50/50 in my eyes. None of them are doing great right now, both struggling in their own league. Napoli just lost to Roma 2-0 Yesterday and Barcelona had a tough victory against Almeria in their last La Liga match. Almeria is the team which is sitting at the bottom of the La Liga. Lewandowski seems out of touch and they have problems in both forward side and the defender side.
I wasn't surprised that Napoli lost to Roma in the Italian League because, once the two players were sent off, there was nothing more they could do. However, I wasn't expecting Napoli to lose to Roma, if the red card hadn't spoiled the game, I thought Napoli would score to win or draw the match. This season, the both team are not playing well, but Barcelona is worse than Napoli.