Drawn in what was on paper a lightweight group featuring FC Basel, Otelul Galati and Benfica, last season's runners-up might have expected to qualify for the last 16 with games to spare.
Instead a combination of poor home form, youthful inexperience and soccer's cardinal sin of underestimating your opponents culminated in the humiliation of a departure from the elite competition into the second tier Europa League.
"We have to look back at the games at Old Trafford. We've not done enough to win those games," defender Rio Ferdinand told MUTV after a 2-1 defeat at Basel on Wednesday sealed their fate and put the Swiss side through alongside Benfica.
"The manager's always said that if you don't win your home games you don't deserve to go through. That's the case this season."
United won only once at home in Group C, a 2-0 victory over Romanian debutants Galati, in a record that was in contrast to last season's domestic form at Old Trafford where they dropped two points on their way to a record 19th English league title.
Sir Alex Ferguson's side only just managed to salvage a 3-3 draw at home to Basel with a late equaliser, while two defensive blunders were to blame for a 2-2 draw at home to Benfica.
Defender Patrice Evra urged his team mates to take a long, hard look at themselves.
"We have to be honest and say we haven't been professional from the beginning of this competition," local media quoted the Frenchman as saying.
"I don't know why, but maybe one or two of us have to look in the mirror and say we can do a lot better than we have done.
"There is always a lesson to be learned because, in the beginning everyone thought United would finish first in the group, with the teams we were drawn against.
"It feels like a dream and that I will wake up tomorrow and we will have qualified. But it is not a dream, it is the reality and we should have woken up earlier in this competition. We deserve to be out."
United's website may have tried to dress things up with a headline "Rio eyes Europa League glory" but there is going to be nothing glorious about playing on Thursday nights having watched the big boys on television the day before.
Evra was under no illusion.
"It is embarrassing to be in the Europa League," he said. "Some players dream of playing for United in any competition and you have to respect that, but the way I feel now, it is Champions League or nothing."
Despite United's declaration that they are going to try to win the Europa League, it is nevertheless likely to take second place to the Premier League and could offer Ferguson the chance to give his younger players some more European experience.
The manager has not been afraid to send his youngsters out on the big stage this season, a move that former United midfielder Roy Keane, now a television pundit, saw as costly.
"People have talked about the young players -
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.