United very rarely bring players in during the January window but it has happened with the likes of Louis Saha, Andy Cole, Nemanja Vidic, Patrice Evra and Diego Forlan joining the ranks.
Benfica's Argentinian midfielder Nicolas Gaitan is in Sir Alex Ferguson's sights and would be of immediate value to the Reds given the reduced options available to the club with a growing injury list. Benfica fans would respond fiercely to any sale in January with many blaming the club's board for loosing the title back to Porto last season, having sold Angel di Maria to Real Madrid and David Luiz to Chelsea within six months of taking their first championship in five years.
Gaitan's agent Jorge Mendes has done business with United in the past but it is thought likely that the Argentinian midfielder will sign for a reported £29.3m plus add ons next summer.
Mendes, who was involved in the transfers of Cristiano Ronaldo, Nani, Anderson, David de Gea and Bebe to Old Trafford in the past eight years.