Barcelona have a number of options in vital positions in the team like in the attacking wings, in the absence of Usman Dembele, Raphinha is available as a replacement for Dembele which gives some level of relief to Xavi as he will not worry much about finding a replacement for Dembele. Manchester United on the other hand are lucky that Casemiro will be available for the first leg meeting against Barcelona and with Eriksen's absence, Sabitzer will fill in and give United some balance in the midfield.
Even though both teams will be minus several players who are absent due to injury, it seems that this is not a problem for the two coaches and they have anticipated this well. The first leg match will take place in a week, of course both barcelona and manchester united must keep their players fit for the match later and I hope that in this week's match in their respective regular leagues, no players will be injured again for both teams.