2. Mats Hummels
Club: Dortmund If Sir Alex decides that he needs an immediate remedy to his aging defensive line-up (or at least the former starting pair), and that money is no option, he will do an awful lot worse than signing Dortmund's other impressive centre-half Mats Hummels. He has been a revelation for the Germans, who are keen to keep him (according to the Daily Mail) - though their resolve might be shaken in the summer if the defender's suitors start to line up to fight it out for his signature. The Express have said that United will face stiff competition for the Dortmund stopper, and that Barcelona boss Vilanova is looking to make a bid for him, so the price is likely to be a big one, but for that money United will get an imperious centre-half who could add the necessary leadership to the backline in the absence of Ferdinand and Vidic.