With Javier Mascherano and Carles Puyol ruled out of Barcelona’s second leg Champions League Quarterfinal against Paris Saint-Germain, Tito Vilanova will have to reshape his defence for the decisive encounter.
If injury to Messi was not enough, Vilanova now also has to deal with the absence of key defensive elements in Mascherano and Puyol ahead of the game against PSG. Although Barcelona have two away goals in their favour, a patched up defence is something the manager would have done without.

However, all is not so bad at Camp Nou considering the fact that the Catalonian do have decent replacements even though most of them are still slightly inexperienced for a game of such importance.

A good pairing at the centre of the defence is vital for Barca’s progression to the semi-final stages of the competition so Vilanova needs to have a good defender who could pair up with Gerard Pique, the only fit and experienced centre-back for tonight’s encounter. At the moment, Vilanova is short on defensive options with young Marc Bartra the only other recognised centre-back.

With just three Champions League games so far this season, one has to say that Bartra might not be given the nod as Vilanova would not want to risk pairing up Pique with a player who has only started getting chances at the club. Furthermore it might not be wise, to give the young defender a start in such a big game, a mistake by him can hinder Barcelona’s progression to the next round as well as hurt the player’s morale.

Alex Song on the other hand, is the only player who Vilanova should see as a defensive partner to Pique for tonight’s crunch game. The Cameroon international has not had a great start to life in Spain but should be the ideal candidate to pair up with Pique in the middle of the defence.

Furthermore, despite the fact that he has not really done as well as he should have for the Spaniards, Song’s versatility is something that the manager will be looking to make full use of against a side that has what it takes to take the tie down the wire.

Song has previously played in the centre back position for his former club Arsenal in a very physically competitive English league, therefore he stands as a top candidate to partner Gerard Pique tonight.

Furthermore, having Alex Song in the centre of defence means that Pique will have a partner who could minimise the threat posed by Zlatan Ibrahimovic and also tame young Brazilian winger Lucas Moura who in the first leg, really made things tough for the Spanish giants.

Paris Saint-Germain know that in order to have any chance of progressing to the next round, they must go and search for goals rather than waiting for things to happen. Like it happened the other night, chances will come for Carlo Ancelotti’s men, which means that Barcelona will have to remain constantly agile in defence.

Also with David Beckham set to start for Les Parisiens again, and knowing his excellent crossing skills it is imperative for Vilanova to have men with good aerial ability at his disposal. Alex Song and Pique are certainly two players who are really good in the air. Furthermore, these two players, unlike rest of their teammates, tend to relish in physical battles.

With someone like Ibrahimovic in attack, who is great at bullying defenders, both the centre backs will have to be at their level best to keep the striker at bay.

Barcelona have always managed to adapt to unordinary circumstances so they could do again tonight if every player manages to do exactly what he is told to do.

As for Alex Song, everyone knows of his quality from his time at Arsenal, and if the Cameroonian can reignite his lost confidence, he can surely be a very important player for Barcelona tonight as well as in future.