Guillermo Varela is set to leave Old Trafford
The two young defenders, aged 22 and 23 respectively, have both featured for the United first-team in recent years, having been blooded by former United manager David Moyes and his successor Louis van Gaal.
With sweeping changes expected at the club following the arrival of Jose Mourinho, who has a debatable record when it comes to working with young players in the past, it is somewhat unsurprising that the two will be shown the door at Old Trafford.
Blackett made his first team debut under Louis van Gaal
Varela was Moyes' first signing, joining from Penarol in 2013 for a reported fee of €2.8 million on a five-year deal.
Blackett came from the famed United academy, signing a professional contract in 2012, but making his debut on the opening day of the 2014-2015 season, sitting at the heart of Louis van Gaal's ill fated 3-5-2 experiment.
And despite going on to make 11 appearances for the Red Devils, with Varela featuring in the Champions League last term, neither player looks to have a future under the stewardship of Mourinho.
Varela (centre) has featured for United in the Champions League
Neither Blackett nor Varela have been training with the United first-team and they have allegedly been told to look for new clubs.
Blackett spent some of last season on loan at Celtic, but he found first-team opportunities hard to come by under Ronny Deila, appearing just three times in Green and White.
Ringing the changes, Jose Mourinho
Varela meanwhile spent the 2014-2015 season on loan with Real Madrid's B side, but returned to feature intermittently for the Red Devils last term, making his debut against West Ham United last December.
He went on to make four appearances for United, but it appears he did not do enough to persuade Mourinho to keep him at Old Trafford for the long term.