By JOHN BOSCHINI

AC Milan and Barcelona are set to square off for the third time in this season's UEFA Champions League as the Serie A leaders welcome the defending European champions to the San Siro for the first leg of their quarterfinal tie.

Lionel Messi arrives in Italy with an astounding 12 goals in this season's Champions League, but Barcelona struggled to impose themselves when the two teams met back in September. Alexandre Pato scored in the first minute, and a 90th-minute header from Thiago Silva earned a 2-2 draw for Milan. Since then, Barcelona have been imperious, winning their next seven Champions League games by a combined score of 28-4.

Zlatan Ibrahimovic will look to notch a win against the team that unceremoniously cut him loose in 2010. The Swedish international has scored five goals in Europe this season and is Serie A's leading scorer.

Bayern Munich will try to end their quarterfinal tie with Marseille as early as possible when the two sides face off in France. Bayern have exploded over the past three weeks, scoring 22 goals in four games while conceding only two. Marseille are struggling in Ligue 1 but have used the Champions League as a forum for success, advancing at the expense of a disappointing Inter Milan side.

Here is a look ahead to both Champions League quarterfinals that are on tap today:

AC MILAN vs. BARCELONA

TV: 2:45 p.m., Fox Soccer Channel

HOW THEY GOT HERE: Barcelona topped AC Milan in a thrilling 3-2 affair at the Camp Nou in November to effectively wrap up Group H a couple of months after their initial draw. In the last round, AC Milan dominated Arsenal 4-0 in the first leg at the San Siro but almost capitulated in London, surrendering three first-half goals before bunkering down and holding out for a 4-3 aggregate victory.

Barcelona were merciless in their thrashing of Bayer Leverkusen in the round of 16. A 3-1 away win gave way to a 7-1 victory at home which featured Messi's brilliant, five-goal performance.

THE LOWDOWN: Barcelona have an aura of invincibility when it comes to Champions League play, but AC Milan shouldn't be overlooked. The front line of Ibrahimovic and a fit Robinho could cause problems for a Barcelona defense that isn't as strong as it has been in years past. An injury to Pato, the loss of Thiago Silva and Ignazio Abate in defense and the suspension of Mark van Bommel for Milan give Barcelona a great chance of taking a road result and a placing one foot in the semifinals.

MARSEILLE vs. BAYERN MUNICH

TV: 2:45 p.m., Fox Soccer Plus/FoxSoccer2Go

HOW THEY GOT HERE: Bayern Munich have been lost in the noise surrounding Real Madrid and Barcelona but the fact remains the German giants have been one of the more dominating teams in Europe this season. They skillfully navigated the "Group of Death" before beating FC Basel 7-0 on March 13. 

Marseille qualified for the quarterfinals in dramatic fashion with an away win over Inter Milan. Brandao scored in the 90th minute to give the French side the aggregate victory on away goals.

THE LOWDOWN: If Marseille is going to pull off the shocking victory and advance to the semifinals, keeping a clean sheet at home is vital. Bayern Munich's weak spot, if they have one, is the ability to score on the road. Former Marseille player Franck Ribery has rediscovered his form and will be instrumental in breaking down Marseille's defense. In terms of key absences, Bastian Schweinsteiger is doubtful for the game while Steve Mandanda, Marseille's starting goalkeeper, is suspended.

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What do you think of today's games? Do you see AC Milan posing a challenge to Barcelona? Think Bayern Munich will coast by Marseille?

Share your thoughts below.