It was hardly the fond farewell that David Beckham would have wished for, as he settled into his seat on the bench and watched his old side humble his new one.
As a United fan, as one reporter commented he could be again, Beckham will no doubt have been delighted with the performance, especially that of Wayne Rooney.
Yet if he wanted to understand where his current club, AC Milan, presently lies in the European pecking order, it was a harsh dose of reality.
As the Italian press picked through the bones of what they described as a “humiliation” with phrases such as “4-0 isn't a defeat, it's a thrashing,” and “The ruins of the old Milan remain at Old Trafford,” it was left to their manager Leonardo to rue what he had witnessed.
He insisted, "To analyse the match now would be out of place.” But the analysis will arguably be as incisive and painful for both him and Milan as the pass from Nani that released Rooney to score his second.
The biggest problem is that Milan's greatest strength has now become its greatest weakness. Their squad contained a total of 10 European Cup winners. With the likes of Clarence Seedorf, Massimo Ambrosini, and Andrea Pirlo, they have a vast pool of experience, which is a great asset.
But after years of aging gracefully, all of a sudden they appear to be showing that the years of playing at the highest level are finally catching up with them.
Individually, this may not necessarily be a bad thing. Lest we forget that Manchester United were fielding Edwin van der Sar, Gary Neville, and Paul Scholes, hardly spring chickens.
But the issue is regarding balance. Whereas United have players such as Rooney, Nemanja Vidic, and Patrice Evra, who are currently operating at the peak of their powers. There are few within the Milan team who could claim the same.
Players such as Klaas Jan Huntelaar, Marco Borriello, and Matthieu Flamini all fit the bill, but seem ill-equipped to lead the team forward. The management may point to the likes of Alexandre Pato and Thiago Silva as the club's future, but at 20 and 25, respectively, it is asking a lot for them to lead the team.
All this leaves the similarly inexperienced Leonardo with an uphill battle, trying to overhaul a club which has for too long relied upon the same group of players with little planning for who should succeed them.
Undoubtedly his task was made little easier by the summer sale of Kaka and the retirement of Paolo Maldini, which robbed the club of their most talismanic presences both on and off the field.
That the charismatic manager has continued to keep the club moderately successful in Serie A is testament to his potential. But for a club with as rich a tradition as Milan, a European defeat in such a manner should have alarm bells ringing.
As Milan Managing Dirctor Adriano Galliani said, "Naturally, it's hard to swallow that the club which has won more international titles than anyone else loses 4-0.”
But, to quote Henry Ford, “History is bunk”, and the reality is that Milan’s rich history counts for nothing in the current face of the footballing present. If their tie with Manchester United taught them anything, it is that Milan’s past need no longer be it’s future.
For all their reliance on players who have achieved much in the game before, it is finding players who have much to achieve in the game which will allow Milan to return to their former glories of European Cup success.
As shameful an experience as Galliani and the Milan management may have found their Champions League exit, failing to learn the lessons from it could be an even more shameful experience.