AC Milan: 10 Lessons to Take into Champions League 2nd Leg with Barcelona

AC Milan hosted Barcelona for the third time this season on Wednesday night. It ended goalless, but it did not disappoint with 90 minutes of enthralling action.

It is a result that leaves the match delicately poised. Barcelona, of course, remain favourites but the Rossoneri will be satisfied due to preventing the Blaugrana from scoring the away goal as it will allow the Italians to progress with a score draw.

UEFA have scheduled the second leg for next Tuesday, so we have a quick turnaround before these two brilliant teams do it once again.

So here are 10 things that we learned from the first leg at the San Siro to keep in mind for the return at the Camp Nou.

Milan Will Regret Missed Chances

AC Milan will regret missing two glorious opportunities.

The Rossoneri may still progress but they will now do it the hard way after failing to take a lead into the second leg.

It has diminished Milan's chances of progression due to Barcelona's imperious home record in Europe.

Barça did draw 2-2 in the group stages to Milan, which would be enough to progress, but other than that, the last result that would be enough to oust the champions from the competition came in 2009 against Rubin Kazan, the Russians winning 2-1 in the group stages.

First it was Robinho who blazed over on the volley from 10 yards out, then Zlatan Ibrahimovic was sent through on goal by a superb reverse through ball by Clarence Seedorf, but his shot was too tame.

One lesson is that Milan will definitely need to be more clinical in the second leg with only a couple of chances created at home.

Opportunities may be even tougher to encounter away from home.

Milan Will Have to Score with a Third of Possession

Massimiliano Allegri has shown us in three matches against Barcelona that he intends to be efficient on the counter attack rather than attempt to dictate proceedings through larger periods with the ball.

In the first game between the sides in the group stages at the Camp Nou, Barcelona claimed 75 percent of possession, then at the San Siro, Milan managed to restrict the Catalans to 62 percent before Wednesday's game saw the visitors enjoy 65 percent of the ball.

Statistics provided by The Guardian.

Barcelona Will Likely Receive a Penalty in the Second Leg

Barcelona will feel aggrieved that they were not awarded a penalty in the first leg of the quarterfinal on Wednesday. 

There were three separate appeals of note at the San Siro that were all ignored by referee Jonas Eriksson.

The first was the strongest appeal as Alexis Sanchez flicked the ball past Christian Abbiati, only to be clipped around the ankles as he attempted to run around the goalkeeper to reach the ball.

The argument against the penalty will be that Sanchez would not have been able to reach the ball before it went out of play, but replays showed the contact was clear.

The second appeal came when Carles Puyol almost scored with a diving header. As the corner was whipped in, Djamel Mesbah was seen to have clearly tugged Puyol's shirt back.

Lastly, Lionel Messi was bundled to the ground by both Mesbah and Daniele Bonera, but again the referee waved play on.

With Milan's physical defending and the extreme pressure that the referee will experience from the Camp Nou supporters, a penalty is very likely to be awarded to the home side in the second leg.

Daniele Bonera Is Vital to Allegri

Daniele Bonera was perhaps Milan's man of the match in the first leg after defending superbly throughout.

The 30-year-old was able to nullify Andres Iniesta, who was substituted early in the second half for the only slightly more effective Cristian Tello, through sheer pace.

Bonera is vital in the sense that Massimiliano Allegri has to contend with the certain absence of Thiago SIlva. Ignazio Abate and Alessandro Nesta will remain doubts also for the second leg.

Bonera is highly capable of filling in at right-back as well as his preferred role as a centre-back. So he will be the natural replacement for the above absentees, especially after showing his capabilities against one of Europe's most potent strike forces.

Alessandro Nesta Is Still World Class

Alessandro Nesta was immense on Wednesday night as he rolled back the years to deliver a vintage display of defending.

The 36-year-old was equal to the challenge of Lionel Messi et al as he was almost faultless in marshaling the Rossoneri defence throughout the game.

Worryingly, the Milan stopper was forced to hobble off injured towards the end of the match and was replaced by Djamel Mesbah which meant a defence rejig, leading to the Rossoneri becoming increasingly vulnerable for the final 15 minutes.

Milan will be hoping Nesta can shrug off his ongoing injury problems in order to maximise their chances of progression to the semifinal. 

Ibrahimovic Must Have a Greater Impact If Milan Progress

Zlatan Ibrahimovic struggled to stamp his mark on the first leg of the quarterfinal on Wednesday.

The Swedish international has been in scintillating form this season, especially in the Champions League, with five goals and four assists in six games.

His only opportunity came after 20 minutes when Clarence Seedorf sent him clean through on goal. Ibrahimovic shrugged off the pressure from Carles Puyol, but could only push his shot weakly in to Victor Valdez's arms.

Ibrahimovic held the ball up magnificently and will need to do so once more, but he will also need to show a more ruthless streak in front of goal for Milan to progress.

Antonini Has Dani Alves's Number

Luca Antonini put in a superb performance against Barcelona to give the Rossoneri faithful confidence he can legitimately be considered one of Europe's top full-backs.

The 29-year-old defended admirably as he nullified one of Barcelona's most potent weapons in Dani Alves, who was marauding down the right flank for the entirety of the match.

The Brazilian international rarely got the wrong side of Antonini and the Rossoneri full-back was able to cover around Philippe Mexes and Alessandro Nesta at times to track the clever runs of Lionel Messi and Alexis Sanchez with their explosive pace in behind.

Antonini will have to be equally as good in the Camp Nou to aid Milan's hopes of progression, whether that be at left-back or right-back, where he operated for the closing moments of the game. 

Seedorf Must Be Rested at Catania for Camp Nou Test

Clarence Seedorf put in a superb performance for Milan on Wednesday and will need to replicate this once again next Tuesday.

The Dutchman added a calming influence to the Rossoneri midfield, as well as a genuine craft and creativity in possession to utilise the little possession his team enjoyed.

Milan face a tricky game away to Catania on Saturday, knowing that a resurgent Juventus are closing in on them, just four points adrift. 

Massimiliano Allegri should rest the 35-year-old for the trip to Sicily, in order to keep Seedorf in optimum condition for the second leg.

Urby Emanuelson, Alberto Aquilani and Sulley Muntari are all adequate alternatives to play in midfield.

Ambrosini Is Superb Cover for Van Bommel

Massimo Ambrosini has slotted in to the Milan midfield superbly in the last few matches with Mark van Bommel out with a back injury.

The Italian veteran showed little signs of being past his best as he shadowed Lionel Messi when the Argentine attempted to drop deep in order to influence proceedings.

Van Bommel is a wonderful player, but Ambrosini is a great replacement, both in terms of experience and energy in order to close down the space that Barcelona utilise so brilliantly.

Allegri Should Highly Consider Maxi Lopez, El Shaarawy for Robinho

Massimiliano Allegri should consider benching Robinho for the second leg.

The Brazilian was not able to lift his performance after missing three matches through injury and was substituted short of the hour for Stephan El Shaarawy.

The Azzurrini international offered more energy in hassling Barcelona's defence and an out ball through the channels to stretch the Blaugrana, particularly down their right flank, which was vacated by Dani Alves.

Maxi Lopez has endured a calf injury after his remarkable impact as a substitute in the Coppa Italia semifinal (coincidentally the second leg) against Juventus.

The Argentine scored a sensational goal to force extra time and returned to the bench Wednesday. He could be called upon to start next to Zlatan Ibrahimovic.

This slide show illustrates the amount of factors that Allegri must consider in order to orchestrate the perfect game plan to dump the champions out of the Champions League.

We eagerly await Tuesday to watch the drama unfold.

Jack Alexandros is a football analyst for Football Radar covering Serie A. You can follow him on Twitter @jackalexandros and @FRcalcioJack.