Leonardo's side are advocates of playing free-flowing, attacking football but even in Serie A, the system leaves them vulnerable at the back. Thiago Silva's displays without the calming presence of Alessandro Nesta are often not representative of his true standard, but the Brazilian was the more composed of the two centre-backs tonight. The ease with which Wayne Rooney beat Daniele Bonera in the air to score the first goal was demonstrative of the reliance that Milan have on Nesta.
Meanwhile on the flanks, the atrocious Ignazio Abate was beaten time after time by Nani, while Marek Jankulovski fared little better against either Antonio Valencia or Gary Neville. The Czech must also take responsibility for the first goal as he failed to close down Neville, while there were several occasions on which Abate simply allowed Nani to cut inside without even attempting a challenge.
Abate is no defender - and had Gianluca Zambrotta been match fit then he would not have needed to fill in at full-back - but clearly these positions need to be addressed in the summer. Had Leonardo had another option to play at right-back, Abate could have been utilised further forward in Pato's position. The youngster is obviously far more comfortable playing in an attacking role, while his pace and delivery could have given Patrice Evra more of a problem.
Instead, the lack of incision from the front three was staggering - Marco Borriello looked as immobile as he had for Italy against Cameroon, Klaas-Jan Huntelaar failed to take a gilt-edged opportunity in the first half and Ronaldinho's passes often failed to find their intended target.
David Beckham's introduction - which received a great reaction from the home fans - gave Milan a far better option on the right hand side, with the Englishman putting in several dangerous crosses, but it was too little, too late from Leonardo.
In the end, it was far too easy for Manchester United to overcome the Rossoneri for the first time ever over two legs of a European tie. Milan's forward line failed to help out their overrun midfield, while the full-backs' limited qualities were exposed for the entire 90 minutes. Sir Alex Ferguson's side were able to contain the Rossoneri with consummate ease after scoring an early goal to heap the pressure on the Italians, while Rooney settled matters with his second goal less than a minute into the second half.
From thereon, it was a matter of how many the hosts wanted to score. Edwin van der Sar was only rarely tested with shots from range - Andrea Pirlo, Mathieu Flamini and Beckham all tried their luck - and in the second half, an uninformed spectator could have been forgiven for thinking that it was Manchester United who were 4-2 down on aggregate.
Unfortunately for president Silvio Berlusconi, Leonardo and Italian football fans hoping that Serie A can cling onto its fourth Champions League spot, Milan's flaws, particularly in their lack of squad depth, were all on display against Ferguson's side. Manchester United can look forward to a quarter-final against one of Europe's elite, but while Milan's challenge of overturning the first leg deficit was almost inevitably doomed to failure, the manner of the defeat will leave a sour taste in the mouths of the Rossoneri.
