3. Mats Hummels
The rock of both Borussia Dormund and Germany's back four for the last couple of years, Hummels may be the next big signing coming through the doors of Old Trafford. Signed from Bayern Munich in 2009
for £3 million, Hummels has made a big impact in making Borussia Dortmund a force in German and European football once again. In his four seasons so far, Hummels has won 2 Bundesliga titles, 1 DFB Pokal Cup and 1 German Super Cup won last week against perennial title rivals Bayern Munich in Pep Guardiola's first official competitive game. He is known for his pace, his sweeper like reading of the game and strength that makes striker's life a nightmare as his last ditch attempts prevent an almost certain goals. It is no surprise that because of these attributes, he is vital towards club and country and would take a lot of money to prise him away and add his experience to the United backline.