The match between Barcelona and MU is still a long time, about 1 month later, with that space, anything change can happen with the squad or team. As I remember several years of situations when a team is favored to win like Barcelona which has a perfect squad has loss meet the underdog team. We can say Barcelona is a team that can not have a problem beating MU, but if 1 of the player have a problem like an injured or can't play on that match, that possible MU will take the opportunity to win and go to the next round.
Indeed, in the match later, one thing that is most feared is if there are major players who suffer injuries during matches in their respective regular leagues. But talking about injuries, sometimes there are some players who get injured during training sessions and that is also something that coaches should be aware of. However, if Man United vs Barcelona later appears with the full main squad, it seems that the match will run more exciting and it will be even more difficult to guess who will win.
Definitely Manchester United vs Barcelona will be so interesting game, Any mistakes from any of the teams will be used as an opportunity for victory. The result will tell if Barcelona is ready for europa league or not , this season it seems Barcelona is just much interested in winning the laliga. Manchester United have been well in the Europa league, they would like to still maintain their consistency.