Barcelona have acted with necessary speed to replace Tito Vilanova. After the Barcelona coach stepped down late last week, there are various reports on Monday that Argentinian Gerardo “Tata” Martino has signed a three-year contract to take up the reins at the Camp Nou. The former Paraguay and Newell’s Old Boys boss joins at a crucial point in Barcelona’s preparations for the new season.

So far this summer only Brazil star Neymar has arrived to bolster a squad that achieved a record points haul in the Primera Division last season but saw their hopes of a third Champions League title in five years emphatically ended by Bayern Munich in the semifinals. Both Martino and Barcelona are likely to be determined to ensure that further additions are made before the defense of their Liga title gets underway on August 18. Here are five possible targets.  

Thiago Silva (Paris Saint-Germain)
There is little doubt where Barcelona’s priorities lie in the transfer market. The club’s refusal to address a weakness in the center of defense was crudely exposed in the bigger games toward the climax of the previous campaign. The top target is clear, with Barcelona’s desire to sign Brazil’s captain no secret and dating back to a failed attempt to bring him to the club last summer. There also appears little doubt about Thiago Silva’s interest in moving to the Camp Nou. The problem for Barcelona, though, is that the former Milan center-back is not the type of character that will look to put pressure on his club to force through a move. And with Paris-Saint Germain neither having the desire or financial incentive to sell, the Blaugrana may again be frustrated.

David Luiz (Chelsea)
Thiago Silva’s partner at the back for Brazil has been repeatedly cited as a target for Barcelona. The reasons are clear to see: David Luiz is exceptional on the ball and at bringing the ball out of defense something that is a hallmark of Barcelona’s philosophy and would aid with Martino’s desire for quick transitions. The former Benfica man is not, though, the kind of lock-down defender that Barcelona perhaps need to play alongside Gerard Pique. Still, he has begun to cut out his errors and his influential demeanor could have a positive impact if he can be pried away from Chelsea at a reasonable price.  

Ezequiel Garay (Benfica)
David Luiz’s replacement at Benfica may also be a target. Garay had a disappointing spell at Barcelona’s bitter rivals Real Madrid but has impressed in Portugal as well as establishing himself as a regular for Argentina. The 26-year-old’s form is believed to have attracted the interest of Manchester United, which has been strongly linked. Yet, Barcelona and Martino may be tempted to step in. Garay is an astute passer for a central defender and, intriguingly, is from the same city in Argentina, Rosario, as Martino, while the player also began his career at Newell’s. One barrier to a transfer, though, could be a reported clause in the deal that saw Garay exit Madrid which prevents him from being sold onto Barcelona.

Ilkay Gundogan (Borussia Dortmund)
With Thiago Alcantara having already left for Bayern Munich and Manchester United pushing hard to sign Cesc Fabregas, midfield reinforcements may be unexpectedly needed at the Camp Nou. At this point in the transfer window, Barcelona may not have a great list of options but they would do well to try and procure a player with the potential to replace the great Xavi, who will turn 34 next January.

Surely, at least high on a potential list of targets would be Germany international Gundogan. The all-round midfielder was instrumental in Dortmund’s run to the Champions League final last season and the combination of his exceptional passing, ability to drive forward with the ball and willingness to work tirelessly to win it back would be an ideal fit at Barcelona. Real Madrid are believed to be working on a deal to bring in the 22-year-old next season and it would be extremely difficult to procure him from Dortmund right now, but it would certainly be worth a try.

Marc-Andre ter Stegen (Borussia Monchengladbach)
It now looks like, barring a late change of plan, that Victor Valdes will see out the remaining year of his contract at the Camp Nou before leaving on a free transfer this summer. That would negate the need for a replacement to be brought in immediately. However, Barcelona may be wise to bring in a goalkeeper now to get give him the opportunity to get to grips with the club before being thrown in at the deep end.

Certainly a stopper as young as 21-year-old Ter Stegen could benefit from that gradual introduction. The Monchengladbach man is highly-rated, having already been capped by Germany, and was strongly linked with a move to Barcelona earlier in the summer. Unlike more experienced keepers like Pepe Reina, with whom Barcelona have also been linked, Ter Stegen also may well be willing to be understudy to Valdes for a season and gain experience in his enforced absence and in the Copa del Rey.