It's disappointing seeing Arsenal get eliminated from the tournament, Arsenal fans will have to watch other teams go on with the competition. Manchester United vs Sevilla is a good pairing as both teams are on good level and able to go head to head, the better team on game days will win that match. I expect Juventus to advance from the match with Sporting, if Juventus can qualify ahead of Sporting then they can be said to be favorites for the trophy this season.
I agree that Arsenal fans must be super angry right now with the way things are looking, they are leading premier league so it looks like they should have been easily beating anyone else as well, maybe fail at United or Juventus whatever but not against Lisbon, that looks like a game they should be capable of winning for sure.
It's the football world, sometimes you can be at the top of the world and then there are some situations where you end up with a loss unexpectedly against a team that you should be winning. Look at Napoli Lazio game just recently, they managed to win against everyone and then ended up losing to Lazio, nobody expected that neither.