Bookmakers gave a 5.6 odds on Porto to win, so few people believed that Porto could win, but even fewer people believed that Arsenal would not score a single goal, the odds on this event were about 5 I think. So Arsenal performed in their usual manner, when they lose important matches unexpectedly, at a time when everyone expects victories. After 11 (!) unanswered goals in the EPL in two matches, everyone expected Arsenal to score at least a goal or two, but Arsenal players decided otherwise. I think Arsenal players still lack athletic aggression and character, but I am happy that they conceded only one goal and now at home there is a chance to get back and go further.
Porto did what they do best, played excellent defense and did not allow Arsenal to make a single shot on target. They managed to do it with a team that scored 11 goals in the last two matches. In addition, from the 80th minute Conceicao replaced four players who had strength and Porto managed to score in extra time, it looked cool. Arteta made only one substitution, I don’t know why this decision was made, but in my opinion, with such a weak game in the Attack, changes were needed, perhaps the reason is that he wanted to bring the match to a draw and was afraid to change anything.
I also think that Arteta wanted to hold on to the draw and was afraid to go on the attack, but still Arsenal conceded on 94 minutes, which once again proves that you can not win the game if the team sits in defense and if Mourinho's Chelsea in his time it worked, now soccer is more combinative and almost all teams are able to pass even the most defensive orders of the opposing teams.
In general, Porto could have scored earlier, but somehow a Porto player, it seems the same one who will score a goal in the 94th minute, hit the Arsenal goalkeeper from a couple of meters.
Porto in general is a very interesting team, like no big stars, but always almost out of their group in the Champions League and even won the Champions League with their modest opportunities.