It was a very painful defeat for Arsenal. They controlled the game but Porto had an excellent defense. Arsenal didn't even have a shot on target. But the match was a painful defeat for Arsenal because Porto was able to score a goal in the 94th minute. I think the match will end in a draw.
But this result still doesn't put Porto in a safe zone because Arsenal is a strong team and a 1 goal lead will only make a small difference. Arsenal will host the second leg so I think Arsenal still has a chance to turn things around.
Arsenal did their best but loosing at that point was inevitable so they lost to porto , they had the best performance a d even out played Porto at some point but it still surprising how Porto still managed to win, maybe it will be fine to say proto were lucky and Arsenal weren't because that sounds like the new description to what happened in that game. Both teams appear to still ha e equal chance but if Arsenal draws in their next meeting they are obviously exiting the champions league and that's without any form of prejudice because Porto is current at the advantage of a win already even if it's with just a goal but they are in a better situation than arsenal currently.
By the next meeting that will be hosted by Arsenal, if Arsenal wins with two goals they may have the opportunity to qualify as against Porto otherwise I their fate may be a totally different one. But I feel Porto wou want to do much better and their confidence at this moment will be quiet strong so Arsenal should prepare for any possible outcome.