hmm, this is also a tough challenge, the next opponent of manchester united in the first leg of the quarter finals will be Lyon, if we look at how lyon performs in the local league then we can see lyon is in 5th position with 7 defeats while manchester united in the epl has experienced 12 defeats and that is really bad statistics. besides that the one who will be the host in this first leg is lyon, this makes their chances of winning even higher, I will not put my money on choosing manchester united, the risk is high, I will just choose lyon, in my opinion their chances of winning are slightly better than man utd.
Man United is indeed performing badly and really has no hope left in their domestic league but don't forget they didn't have the same fate in the Europa League, where you could even say their performance was quite good. If Amorim really prioritizes the Europa League above all else, I am pretty sure that Man United has a big chance to win the trophy, and I think I would also dare to bet on their victory in the next match.
The truth is that manchester united is unpredictable, which is why people don't always have confidence when betting them. Because their performance is very fluctuating is not always stable. Is just like that of their previous match against real socieded majority of this gamblers was also avoiding them from the early stage, but to their greatest surprise manchester united end up gaining victory over them. So even if you choose not to include them in your betslip, but I guess you have heard about this saying that what most be most be.