The Red Devils were overrun in midfield and defense by a younger, more powerful and dynamic Spurs midfield. And in defeating Sir Alex Ferguson's side for the first time in 23 years, Tottenham exposed flaws in Sir Alex Ferguson's selection policy.
Here are three lessons from United's defeat to Spurs.
Manchester United's first half performance and the clear positive influence the substitution of Ryan Giggs had on United's performance was a sign that some of Sir Alex Ferguson's midfield picks were off.
Just as in the game against Liverpool, Sir Alex Ferguson's midfield could not cope with the speed and power of the opposition. In the game against Newcastle—albeit Newcastle's second string side—we saw a more dynamic Manchester United midfield in the form of Anderson and Tom Cleverley.
In both the Liverpool and Tottenham games, both midfielders were unused subs. Hint?
The upturn in United's play and Wayne Rooney's introduction was not a mere coincidence—the Manchester United striker turned provider for United's first goal of the game which Nani slotted in and hit the post as United tried to stage a comeback.
Rooney effectiveness in the final third was matched by Robin van Persie and Shinji Kagawa, and all three had ample opportunity to score decisive goals for United, showing that a United team could accommodate all three players to good success.
Manchester United's defense has proved leaky to say the least so far this season and some of it down to United's injury woes in defense—Phil Jones and Chris Smalling have been sidelined with long-term injuries—however, that isn't an excuse for United's recent poor performances in defense.
Rio Ferdinand, for one, has struggled to keep up with the pace of the League, and Patrice Evra has lost all sense of what a full-back should do.
Using the Spanish and English champions as comparisons: Were it Real Madrid or Manchester City, Marcelo or Clichy would no doubt be (and have been in the past) replaced by Fabio Coentrao or Aleksandar Kolarov—even Sergio Ramos was dropped for Madrid's key Champions league game against Manchester City. Why should it be any different at United? Why all the protectiveness?