Even though the situation is very difficult, Manchester United still has a chance to qualify for the round of 16. The only way for Manchester United to qualify for the last 16 is to win against Bayer Munchen and hope that the match between Copenhagen vs Galatasaray ends in a draw. Even though it's tough, in football anything can happen.
These two things are quite difficult for Manchester United because the opponents they face are quite tough opponents in Group A so far and Copenhagen and Galatasaray will also try their best to win so they can qualify for the next round. Because Copenhagen and Galatasaray are both very aware that they also have the opportunity to qualify for the next round if they can win their final match in Group A. So this will certainly be quite difficult for Manchester United in their last match because apart from having to hope to win, they also have to hope that the other side's match ends in a draw.