Barcelona vs. AC Milan: 7 Key Battles to Watch in Champions League Quarterfinal

Friday's UEFA Champions League quarterfinal draw ensured that a highly anticipated Barcelona-Real Madrid final is a possibility. In order for a combination El Clasico/European championship showdown to happen, though, Barcelona will have to get past Serie A leaders AC Milan.

That's far from a given, despite Barca's win over Milan at the San Siro in the group stages back in November. The Rossoneri gave the defending champions a test over two matches and managed a 2-2 draw at the Camp Nou. 

Milan has few obvious advantages, but on their best day they're capable of shocking the Catalans.

Top-level matchups all over the field make the tie the clear choice for most intriguing of the round. Whichever club emerges looks like a good bet to reach the final in Munich.

Naturally, this is the worst possible draw for Milan.

Coming off their near collapse against Arsenal at the Emirates in the last round, Milan's European fortunes now run up against a Spanish buzz saw. The question bears asking: If Robin Van Persie and the Gunners can torch Milan's defense in game in which the Italians simply needed to hold on to their first leg advantage, what will Barcelona manage?

Meanwhile, Barcelona's league campaign looks to be a lost cause, meaning the Blaugrana's singular intention is to retain their European crown. 

Keep in mind that most of the focus will be on Barcelona's attack versus AC Milan's defense, but that Milan present their own level of offensive threat. Here are seven matchups to watch when Barcelona travels to Milan to begin the battle on March 28th. 

Zlatan Ibrahimovic Versus Barcelona's Central Defenders

All eyes are on Zlatan, at least when Milan have the ball. Big, strong, fast and clinical, the Swede is the focal point of the Italians' attack and is averaging nearly a goal a game in both the league and Europe.

Zlatan's history with Barcelona and Pep Guardiola makes for juicy subtext, and while it might provide further motivation for the Milan striker, he hardly needs it to turn the tie on its head.

When it comes to stopping Zlatan, the task will likely fall to Barcelona's experienced centre-back pairing of Carles Puyol and Gerard Pique.

It's a foregone conclusion that Barcelona will control possession—that means tracking Ibrahimovic's runs the handful of times Milan is able to put together a cogent attack and preventing Zlatan from getting good looks on goal.

Frustrating Ibrahimovic by staying close and preventing him the space he needs to create shots will go a long way toward keeping off the score sheet. 

Andres Iniesta Versus Mark Van Bommel

The center of Barcelona's formation is the domain of Andres Iniesta.

As the conductor of so many of Barca's tiki-taka movements, the diminutive midfielder is an anchoring sun around which the rest of the team orbits.

AC Milan's Mark van Bommel is a ball-winner—the man tasked with making Iniesta's job difficult. Van Bommel won't shy away from knocking his opponent over if that's what it takes. In fact, "knocking his opponent over" is often van Bommel's default setting.

There's subtext here as well, with the two midfielders having battled on big stages several times over the last few years—most notably in the 2010 World Cup final. Van Bommel knocked Iniesta over and Iniesta scored the winner. 

The battle between the pair in the center of the field, and whether Iniesta can find the time and space to initiate Barcelona attacks into the Milan defensive third will be the tone-setter for the tie. 

Massimiliano Allegri Versus Pep Guardiola

We can't talk about Barcelona vs. AC Milan without addressing the two managers involved. Tactics matter, but more important to ultimate outcome might be team selection. 

The last time the two sides faced off, Milan nearly stalemated the dangerous Spaniards. Both sides had injury absences though, with Guardiola's side in particular affected by the lack of Gerard Pique, Dani Alves, and Andres Iniesta. 

This time around, Barcelona is faced with the sudden loss of Eric Abidal, whose setback from cancer treatment means the fullback now needs a liver transplant. Allegri also has injury concerns at the moment, with Robinho, Boateng, van Bommel and Abate all out of action as of this writing.

The tie, particularly the first leg in Milan in two week's time, could turn on how Guardiola chooses to cover for Abidal and whether Milan's stalwarts are fully recovered. It would be wrong to assume that both will stick with the same teams that last battled in November. 

Allegri might see Abidal's absence as a weakness to exploit, while Guardiola will likely pick his team simply based on player availability and the usual Barcelona desire to play the same way no matter the opponent.

Christian Abbiati Versus Barca's Attackers

Like every keeper that goes up against the Barcelona juggernaut, Christian Abbiati is certain to play a large role in whether his team can get past the European champs.

If Abbiati can make a few saves he has no business making, and if the Milan defense can stay disciplined enough in the face of the Barcelona onslaught, the Italian side's offensive threats provide a chance to pull the upset. 

Much more than his opposite number, Victor Valdes, Abbiati holds the fate of his team in his hands.

Conceding early to the defending champions is a recipe for disaster, and if the Milanese are to have any hope in the return leg at the Camp Nou, Abbiati and his defensive cohorts will have to keep Messi and Co. in check.

Eric Abidal's Replacement Versus Milan's Right Side

This battle is a little difficult to frame since we don't yet know how Guardiola will cover for Abidal's sudden absence in the Champions League.

Adriano is the most likely candidate to slot in; the Brazilian stepped into the left back spot on Saturday in Barca's La Liga match against Sevilla. As long as Guardiola sticks with a 4-3-3—and there's no reason to think he won't—dropping Adriano into the defense makes sense. 

It's not as though Barcelona hasn't had to make due without Abidal before, but the nature of his departure from the team could have wider ramifications.

Adriano is a capable player, but not quite the defender his French teammate is. Milan should find more space behind the Brazilian than they would with the more defensive-minded Abidal on patrol.

Leo Messi Versus Milan's Defensive Line

The key to containing Lionel Messi—well, the key to keeping him from beating you all by himself, anyway—is to limit his deadly darting runs behind the defense.

Messi eats defenses alive by timing his movement perfectly with passing from the cadre of talented Barcelona midfielders. Even when marked aggressively, the Argentine finds a way to slip through, and we know what he does when it's just him and keeper.

The problem with keying on Messi, of course, is that Barcelona possesses a host of other weapons that can tear apart a defense. The Catalan side pressures defenses into choosing, which threat to shutdown, all the while hypnotizing their opponents with their short passing game, thereby forcing mistakes.

Rarely does Barcelona let a defensive mistake go unpunished. 

Kevin-Prince Boateng Versus Sergio Busquets

AC Milan's Kevin-Prince Boateng has turned in a solid year for the Serie A leaders—a complement to the cagier talents of Zlatan Ibrahimovic—the Ghanaian's speed and power make him a formidable challenge for any defense. 

Consistency has typically been Boateng's problem. Now that he's found some, he's an integral part of Milan's Serie A and Champions League campaign. Used as the one in Allegri's 4-3-1-2, he plays both scorer and provider in the Milan attack.

The challenge rests squarely on the shoulders of Sergio Busquets, the Barcelona midfielder most often asked to put in a tackle. Busquets defensive responsibilities will bring him into direct conflict with Boateng when Milan pushes forward. 

How often he'll be asked to battle Boateng depends on Milan's ability to maintain a semblance of possession.