It has been no secret that the back line of Manchester United has been aging out in the last few years.
The retirement of Gary Neville signaled the ending of the guard, and departures of long serving members Wes Brown and John O'Shea to Sunderland over the summer continued that trend.
Rio Ferdinand has been a walking injured liability for the last few seasons as his appearances are gradually decreasing as time and age take a toll on his frame.
Nemanja Vidic likewise has started to succumb to multiple injuries and has hardly been seen in Red this season. Soon to be age 31, leftback Patrice Evra is also on his way out in due time.
There is hope in the youth that the club have, but time will need to see how the next wave of Phil Jones, Chris Smalling, Jonathan Evans and the Da Silva twins, Rafael and Fabio, will fare.
Even then there is room for additional players as the amount of games that the club play warrants having two quality options for each position in the long run.
Manchester United have started to rebuild their strong defense in the right way including much criticized goalie David De Gea, who is just as much a part of the defense as his four guardians.
Now it is up to Sir Alex to bring in the final pieces of the puzzle that will see United return their defense to the fortress that it has proven to be in the past.
However, you cannot fail to mention that the German has been a major target of the Red Devils and would be a great signing to secure the longevity of the back line for the club.
Even though he is not looking to leave this summer, that does not mean next summer couldn't see a change of mind from both player and club.
Valencia's rising star defender Adil Rami is attracting much attention from Sir Alex Ferguson at Manchester United.
Having been part of Lille's French title winning side last season before returning to Valencia on loan, the 26-year-old is well aware of the pressures of being at the top of the league and could be a great fit for the Red Devils.
Barcelona's Gerard Pique could make a surprise return to Manchester United after having left Old Trafford for the Nou Camp several years ago.
It seemed that England was just not working out, but his move to Spain has seen the player rise to his full potential and become part of arguably one of the best teams to grace the pitch all time between 2009-12 under Pep Guardiola.
With right back being occupied by whomever Sir Alex decides is right at the time between Rafael Da Silva and Chris Smalling, he continues to struggle with securing a player that will be the long-term successor to Gary Neville.
Nice youngster Diacko Fofana could be the next possible solution as his £5 million price tag according to TalkSport is well within reason for the club.
At 17, Fofana will also have plenty of time to develop behind players like Chris Smalling, Rafael and brother Fabio Da Silva and at times Phil Jones on the right.
Udinese and Morocco defender Mehdi Benatia is hopeful that he can be one of the new generation at Manchester United as the player has issued a come-and-get- me notice to Sir Alex Ferguson with his comments in The Sun:
"They are the biggest club in the world, and to have an opportunity to play at Old Trafford would be amazing, believe me.
"But I have a contract with Udinese, and they have to be happy before I can move."
Metro has also quoted the player as calling a move to England's biggest club a "dream come true."
Borussia Dortmund defender Neven Subotic has been linked with Manchester United for sometime now.
The Serbian international defensive teammate of current Red Devil Nemanja Vidic was tipped as the man to replace Rio Ferdinand in November of 2011 by Metro.
Most recently he was linked to the club by the Daily Mail in February 2012.
Just as with Mats Hummels, Subotic could be extremely costly for Sir Alex Ferguson to acquire, and cost might end up being the stumbling block.
Sometimes despite all the transfer speculation, you have to sit back and remember what you already have at your disposal as well when you look at the future.
Manchester United have some of the best young defensive talent in the league between Phil Jones, Chris Smalling and Jonathan Evans.
Both Jones and Smalling have already made their full international debuts for England and have been impressive since coming under the wing of Sir Alex Ferguson.
Evans has grown through the ranks more so than his newer teammates but has been excellent all season standing in at different times for the long-time injured veterans Nemanja Vidic and Rio Ferdinand.
Jones, Smalling and Evans all have a bright future and should not be left out of the equation for those that can have Old Trafford being a clean-sheet fortress well into the future.
Manchester United are sure to add at least one new defender this coming summer out of necessity if nothing else.
The Red Devils have proven time and again that they can rebuild with quality new talent under Sir Alex Ferguson, and I expect nothing less of them as the old Scot continues to prove his ability to lead.