Nobody can predict what will happen on the field. Last season Liverpool came into the UEL as favourites, they managed to win every game before Atalanta stopped them. This season there will be a new champion in UEL, Lazio is the most consistent team so far, but that doesn't mean they can win the trophy at the end of the competition.
I don't think Man United are capable of competing in the title race, just look at their performance in the EPL, they always get minor results even though the opponents they face are not too strong.
Manchester United still have to make a more accurate improvement in themselves in this season and if Manchester United is able to make a more attractive surprise in the European League this season, I will also not be surprised by that. Because it is true that as you say that in the European League it is always quite difficult to make predictions from the beginning because of the changes can still occur through every surprise in a team that is not favored so far. Lazio is already quite great in the European League this season, but teams like Lyon, Galatasaray and Tottenham Hotspur must also be watched out by Lazio.