Mats Hummels
Mats Hummels has been in impressive form for Dortmund this season.Reuters

Manchester United are preparing a bid for Borussia Dortmund defender Mats Hummels as replacement for Rio Ferdinand, according to the Daily Express.

The German centre-back has been a long-term target for United, who will be hoping that the soon-to-be-announced manager, Louis van Gaal, will be able to convince the defender to make the move to Old Trafford, having previously worked with him at Bayern Munich.

Hummels is the mainstay of the German defence and will be a brilliant replacement for the 35-year-old, who has been among the best defenders in the league during his prime.

The defender is unlikely to come cheap but the Red Devils are confident that they can stomp up enough cash to convince Dortmund to sell and it will be a major boost in their bid to secure a Champions league spot yet again next season.

United currently have Phil Jones, Chris Smalling and Jonny Evans in the centre of defence, with Nemanja Vidic making his way to Inter Milan.

The duo of Ferdinand and Vidic has been among the most vigilant in England and any player coming in will have major boots to fill.

Ferdinand, who was reportedly snubbed in his attempt to sign a new contract, bade his farewell to Old Trafford on Sunday as he looks to move away in search of opportunities elsewhere.

"I joined Manchester United in the hope of winning trophies, and never in my wildest dreams could I have imagined how successful we would be during my time here. There have been so many highlights, playing alongside some great players who have become good friends, winning my first Premier League title and also that fantastic night in Moscow are memories that I will cherish forever," Ferdinand told United's official website.

"Circumstances didn't allow for me to say goodbye the way I would have liked but I'd like to take this opportunity to thank my team-mates, staff, the club and the fans for an unbelievable 12 years that I'll never forget. Winning trophies I dreamed about as a kid came true at this great club.

"I am feeling fit and healthy, ready for a new challenge and looking forward to whatever the future holds for me," he concluded.