Barcelona are considering moves for Manchester United captain Nemanja Vidic and Borussia Dortmund star Mats Hummels, according to Italian publication Calcio Mercato.
The Catalan giants have been ravaged by defensive injuries this season, most notably to Carles Puyol and Gerard Pique, forcing Tito Vilanova to deploy midfield duo Javier Mascherano and Alex Song in central defence.
Sporting Director Andoni Zubizarreta has been tasked with finding at least one player in January that could fill the void left by the two Blaugrana stars, and Sir Alex Ferguson's Serbian stopper is believed to be their primary target.
The 30-year-old is under contract at Old Trafford until 2014, but that has not prevented speculation linking Vidic with a move away from Manchester United, prompting his agent to come out and quash rumours his client is poised for an exit.
United have also been credited with an interest in signing Dortmund defender Hummels, who penned a new five-year deal with the Bundesliga giants as recently as the summer.
The 23-year-old is regarded as one of the best centre-backs in the world, and is also courting admiring glances from Barcelona, who could deal United a double transfer blow, by making moves for one of their current players, and another of their prospective targets.