United were strongly linked with another La Masia graduate in Thiago Alcantara before he agreed to sign for Bayern Munich on Sunday and it appears the club have quickly switched their focus to Fabregas.
Various broadcasters and national newspapers have all reported that United have made an official approach to Barcelona in an attempt to prise the World Cup and twice European Championship winner from Camp Nou.
The Spain international rejoined his boyhood club in 2011 when he transferred from Arsenal in a deal worth a potential £35 million and has won the Copa del Rey and La Liga with Barca.
Last season Fabregas started 30 games in La Liga, scoring 11 times and claiming 11 assists, and the 26-year-old would add some much-needed quality to the United midfield.
However, given that Barca’s midfield options have been weakened by the loss of Thiago and that Fabregas is a dyed-in-the-wool Catalan, United likely face a difficult task in bringing him back to England.
Fabregas said in June: "People talk a lot but the truth is that no-one has spoken with me. I want to triumph in Barcelona, that club is my home and I always dreamed of playing there, so I will try and succeed there as long as I can."