Barcelona keeping tabs on Borussia Dortmund's Mats Hummels - report

The Catalan giants have already begun planning for next season after compiling an initial list of defensive targets to pursue, with the Germany international leading the pack
Borussia Dortmund defender Mats Hummels has gained the interest of European champions Barcelona, according to Spanish source Sport.

General manager Andoni Zubizarreta has been quietly working behind the scenes to plot potential new arrivals for the defending Spanish Primera champions, and it is a defender that is reportedly the priority for Pep Guardiola.

The 22-year-old Hummels has become a wanted commodity after a memorable breakout season with Dortmund, who won the Bundesliga title last season thanks to a water-tight backline that conceded just 22 times.

His versatility has also reportedly impressed Zubizarreta as he can also be deployed as a defensive midfielder, but it has been his consistently impressive performances for club and country that have showcased his intelligence, distribution and positional awareness.

However, there are several stumbling blocks that lie ahead of a possible transfer. The defender recently turned down a move to Bayern Munich in favour of penning an extension until 2014, reportedly cancelling out a release clause in the process. The duration of his deal, coupled with reported competition from Juventus, suggests his services will not be procured easily.

If a move for Hummels does not come to fruition, then AC Milan's Thiago Silva and Valencia's Victor Ruiz form the two other names on the shortlist.