Thiago Silva
Thiago Silva is Barcelona's first choice to strengthen their defense. Reuters

Barcelona are continuing their attempts to bring in a leading central defender to strengthen their backline ahead of the new season. After failing to sign a center-back last summer and instead recruiting midfielder Alex Song, who they hoped could fill in at the back, Barcelona’s defense was found wanting in several big matches in the past campaign. And it is the player that the Spanish champions missed out on 12 months ago that they are now desperately trying to bring to the Camp Nou.

Thiago Silva honored his commitment to go to Paris Saint-Germain when Barcelona came calling a year ago, but, according to Marca, he is now keen to make the switch. The Spanish sports daily believes that the fact that the manager who signed him for PSG, Carlo Ancelotti, has now left for Real Madrid, means he no longer feels he owes the club his loyalty. The Brazil international recently revealed that Tito Vilanova approached him again about joining Barcelona when the sides met in last season’s Champions League.

But his release still promises to be extremely difficult. PSG have repeatedly insisted that the 28-year-old will not be sold and the club is unlikely to be tempted by any transfer fee that Barcelona can offer. With that in mind, Barca are certainly not putting all their eggs in Thiago Silva’s basket.

Fellow-Brazilian David Luiz has long been linked with Barcelona, with his ability on the ball making him a natural fit for the Blaugrana’s style of play. British tabloid the Daily Mail has claimed that the club have taken their interest a step further and made a £30 million (€34.9m) bid for the Chelsea defender. Despite becoming an increasingly impressive and influential presence at Stamford Bridge, there has been talk that new Chelsea manager Jose Mourinho would not be adverse to moving him on. Yet the Mail states that Barcelona will have to up their bid.

If Barcelona are unwilling to do that then they could move for Liverpool’s Daniel Agger, who is also said to be on the radar. The Liverpool center-back, who was the subject of a rejected bid from Manchester City last summer, is accomplished coming out of defense. And, according to Barcelona-based paper Mundo Deportivo, the Denmark international was the subject of interest from Barca before Seydou Keita’s exit led to the decision to sign Song instead. Agger, 28, would likely be tempted by a move and the chance to return to the Champions League but Liverpool are unlikely to be prepared to sell for much less than €30 million.

Barcelona may also be forced into an unplanned move in the summer transfer window if Thiago Alcantara decides to join Manchester United. Mundo Deportivo has put forward the names of several players that the club would be interested in to replace Thiago, who has a clause in his contract allowing him to move for €18 million until the end of July, One of those mentioned is Arsenal midfielder Jack Wilshere.

The England international would appear a perfect candidate to fit seamlessly into Barcelona’s short-passing style. However, Wilshere is an integral part of the Arsenal squad and it would take a massive offer to pry him away from the Premier League side. Barcelona’s best hope may be if Arsenal continue to under achieve and Wilshere’s head becomes turned by the opportunities for trophies on offer at the Camp Nou.

Follow Jason Le Miere on Twitter