There was no winner in the Napoli-Barcelona match. Napoli managed to draw with a terrible game at home.Barcelona has the potential to beat Napoli, but it seems that things are not going well for them either.At least it's a good enough result for Barcelona.They will win the next match at home and go through.
I didn't expect Arsenal to lose.I thought the match was very unpleasant because only 2 of the shots taken by both teams during the 90 minutes were accurate, one of which was a goal in the last minute.Arsenal, despite playing well, couldn't be very effective in front of goal against Porto and left with a goal in the last minute.Arsenal will have to show an extra performance at home now.
I agree with you that Barcelona will win against Napoli in the second leg of the UEFA Champions League Round of 16 matches. Napoli's performance against Barcelona was poor. Napoli just managed to have one shot on target against Barcelona, which led to a goal that earned them a draw. With Napoli's present form, it will be hard for them to beat Barcelona at Camp Nou.
I myself did not expect that Arsenal could be defeated by Porto, even though I was very confident with Arteta because in the domestic league they were in a very good game, while Porto underestimated the team a lot because it was based on the popularity of a different league, but Porto could beat Arsenal well. Arsenal will have to beat Porto in the second leg by a bigger score.
Likewise, Barcelona were quite surprising to get a draw against Napoli, but it is true that if only Barcelona draw if they can beat Napoli at home then they will be very sure to qualify for the next round, the second leg is a very important bet.