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After FC Barcelona were embarrassed and eliminated by FC Bayern Munich in the UEFA Champions League semifinals, el blaugrana will look to reload—not rebuild—for the 2013-14 season.

The first and most important step in reloading will be to bring in a solid centre-back to solidify the Barcelona back line, which has been the weakness of this team for years now.

For almost two years, I have been mentioning the name of a young German defender named Mats Hummels to be purchased. Mats' name was first brought to my attention when I read a blog that stated Hummels is a rising star in the Bundesliga. After watching a few Borussia Dortmund games on TV, I noticed this kid was in fact the real deal.

I do believe he is part of the solution to make this FC Barcelona team greater than it's ever been.

Euro 2012 only further proved Mats is a top-level defender. He dominated in games against Portugal, Denmark and the Netherlands. His height, instinct and ball control were too much for opponents.

Albeit Mats had a few injuries this Bundesliga season and BVB were not able to three-peat as German champions, but Hummels had a solid 2012-13 Bundesliga season. And Hummels' UEFA Champions League run has been terrific.

In the first leg of BVB's semifinal matchup against Real Madrid, Hummels made an error on defense, which lead to Madrid's lone goal of the game. After the play occurred, many fans and even so-called "football experts" were ripping Hummels. I even saw tweets that said his mistake was the reason Mats is not a top-25 defender in Europe.

What a joke!

One mistake doesn't throw away a player's skills or accomplishments. Mats made a mistake, and it could have been a costly one. But let's not act like he is no good because of it. These mistakes happen.

Hummels shut up those same critics and showed all of us why he is one of the best centre-backs in the world in the second leg of the Champions League semis against Real Madrid. Mats kept Gonzalo Higuain's runs in check, he headed out any cross into the box as well as Madrid corner kicks, he came up and headed out long passes by Madrid's midfielders and defenders and he stepped up to stop runs by the Madrid forwards.

A stellar performance by Hummels which earned him Man Of The Match honors.

After the BVB/Madrid game, my first thought was A.) Why can't FC Barcelona have a defense like that?, and B.) Sandro Rosell must do everything in his power to bring Mats Hummels to Catalunya.

After watching the Barça/Bayern game on Wednesday, it reiterated everything I thought about about after the BVB game.

Hummels would help Barcelona defend set pieces, as well as corner kicks—two big areas of weakness in the Barça defense. At 6'4", Hummels and his long legs are able to slow down speedy forwards like Cristiano Ronaldo. He is also solid at clearing crosses that come into the box. And as we saw against Bayern Munich—in particular, the Gerard Pique own goal and the Thomas Müller goal—FC Barcelona are not the best at clearing crosses and can use more height in the back line.

While there are other options for a new centre-back, in my opinion, I don't think any of them are as solid as Hummels. Thiago Silva is an amazing CB, but he is a few years older (28) than Hummels (24), and Paris Saint-Germain will be very hesitant to sell a player they paid AC Milan so much for just a year ago.

Vincent Kompany is another name linked to a Barça move, and is probably the best alternative for Sandro Rosell if he is not able to acquire Hummels' services. I'm certain Manchester City will ask for a few Masia products in return—perhaps even young CB Marc Bartra or Marc Muniesa as part of the deal. For me, I'd sell Muniesa in part of a Kompany deal, but Bartra is off limits.

Finally, AS Roma's Marquinhos is a name that has come up. I haven't seen too much of this kid play, but after everything I've seen and read, the Brazilian has all the traits to become a future superstar defender. But I don't know what to feel about acquiring a 18-year-old and placing him on the Barça defense, asking him to essentially be the heir to Carles Puyol's CB throne. Plus, the kid is still very inexperienced, having never appeared in European competition or even the Brazilian national team's first squad.

For me, I see Mats Hummels as the best option for Sandro Rosell to purchase for this Barcelona team. He has the big-game experience and his defensive style of play fits well at Barça. As an added bonus, Mats has shown that he can play well against Real Madrid.

It is estimated that Hummels would cost Rosell €25-30 million. The Barcelona budget would allow a purchase of Hummels.

A few weeks ago, Mats told Sport Bild (via Sky Sports) that he would listen to an offer from Barcelona:

My father and I have turned down about 99.9 per cent of all the clubs in the world when they come to us. But Barcelona are one out of the two or three clubs that could make me consider a possible transfer. I would see whether it makes sense or not to leave.

With Borussia Dortmund losing Mario Gotze to Bayern this summer and Robert Lewandowski potentially leaving as well, it will make more sense for Mats to leave Dortmund this summer. The team will not be as competitve as they were in 2012-13.

In an interview with a German TV show (via ESPNFC), Sandro Rosell hinted at a Mats Hummels purchase. “There is a German player who I like a lot, but I cannot say his name,” he said. “If, in the end, we go for him, that would drive up the price.”

There is no doubt Rosell was hinting at Hummels.

My hope is that if Mats Hummels is signed, his work ethic and play can rub off on Gerard Pique and make him a better CB as well. Gerard's game has slipped this season. Pique's own goal against Bayern in the second leg of the Champions League semis was the icing on the cake for a very down year for Shakira's baby daddy.

As far as Marc Bartra is concerned, I like the kid, and I'm glad he has gotten plenty of playing time with all the injuries to the back line. That being said, I feel the kid is not ready to be a full-time starter for Barcelona. He's made a few mistakes in CL games, he needs to gain more muscle and he needs to mature football-wise just a bit more.

One last thing: I have not forgotten about Carles Puyol. He will be back next season, and he's still el capita. But we all know Carles is past his prime. He still has strength, but age has taken his speed and his endurance. Carles is no longer a full-time starter.

FC Barcelona needs to finally address the defense with the signing of a true centre-back. While there are good options out there, in my opinion, there is no better option than signing Mats Hummels.

He's proven himself in the Bundesliga, with the German national team and with Borussia Dortmund. And in this season, Hummels has shown all of us that he could be the centre-back FC Barcelona desperately needs.

FC Barcelona's summer will be a busy one.

Neymar to Barça is essentially a certainty.

But the summer transfer window must start with addressing the Barça defense.

And Mats Hummels is the best option for FC Barcelona.

Vamos!

Xoel, The Voice of FC Barcelona.

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