Barcelona vs Manchester United match has now become the main object of Europa League discussion. But I still have little fear for clubs like PSV, Roma, bayern leverkusen, midtjylland and Monaco. This clubs are doing well in their league but their chances of winning their league is much quite narrow compared to their chances of winning the Europa League, for that they might show much more curiosity in winning Europa league matches than clubs like Barcelona and Arsenal. Therefore one should not underrate them in Europa league matches.
I don't expect too much from Midtjylland honestly. Their huge victory over Lazio shouldn't be misleading. I think it was just due to Lazio's not focusing on that match most probably. In addition to that, Lazio had their revenge on them by a 2-1 victory in Italy later on.
The teams remaining are powerful ones of course. None of them deserves to be underestimated. Roma, Leverkusen and Monaco are teams that are quite away from the leader in their domestic leagues now. Therefore this trio might decide to focus on the Europa League title a little more. PSV are in a great championship race with several teams in the Eredivisie. Their job is more difficult as they will need to keep both tournaments balanced. However I think they are still strong enough to eliminate Sevilla. Because Sevilla are having really bad days.