4. Marcelo
The Real Madrid left-back has been a strong player for Madrid in recent years. Being in an attacking minded team like the Spanish giants usually means that Marcelo is often over looked when it comes to praise. The 25-year-old Brazilian born defender has been a solid member of the Madrids back four in recent years but hasn't appeared as much in the 2012/13 season. The defender has been somewhat left out La Liga having only started 13 times for Madrid, partly due to injury. Marcelo's main weakness is the fact he likes to push forward. A defender who has attacking desire is great to see, as Uniteds right-back Rafael also has that tendency, but on several occasions Marcelo finds himself lost in the excitement of pushing forward and seems to forget he needs to get back in position before the opposition counter. Whilst he may have his weaknesses, at just 25-year-old he still has a considerable amount of time left at the top level and could be highly beneficial to Manchester United.