It was reported by Paul Hirst of The Times that Sanchez is feeling "lonely, bored and ignored" at Old Trafford, and despite only joining the club in January he is keen to leave United to sign for Paris Saint-Germain.
However, James Ducker of the Daily Telegraph wrote that while manager Jose Mourinho will allow defenders Marcos Rojo and Eric Bailly to move on in the upcoming window, Sanchez is unlikely to be sold:
"Sanchez has struggled to settle in the north west and is understood to be looking for a way out of Old Trafford only 10 months into a contract that runs until June 2022.
"But his dire form and the enormous costs involved in signing a player who will be 30 next month are deterring any would-be suitors, and the only prospect of a parting of ways would involve huge financial sacrifice on both sides or a heavily subsidised loan and, for now at least, neither party will entertain that."
As Ducker noted, United swapped Sanchez with Henrikh Mkhitaryan and are paying the former Arsenal man a weekly wage of £500,000.
While eyebrows were raised at the time as a result of that amount, the deal was still deemed to be a coup for the Red Devils, as they appeared to be getting one of the best forwards in European football.
Per WhoScored.com, Sanchez made a big impact in his three-and-a-half years with the Gunners.
However, since arriving at United the verve and aggression that the forward was renowned for have been almost totally absent.
Sanchez toiled at times towards the end of the 2017-18 term, netting just three goals following his move in January. There was a hope that with a summer off and a full pre-season under his belt with his new club that this season would be a more prosperous one for the player.
While Sanchez did grab a crucial late winner in the 3-2 victory over Newcastle United, he's been disappointing again and has failed to establish himself as a regular first-team player under Mourinho.
Kieran Canning of Agence France-Presse couldn't resist a joke at the player's expense recently:
It's been quite the fall from grace for Sanchez, and as Rafael Hernandez from Barcelona fansite Grup14.com noted, things could've been so different for him:
Given the fact he's 29, he's on an enormous salary and he's not performed at a high level for approaching a year, it would be a big shock if any elite side made a serious effort to sign Sanchez in January.
For the time being, the best course of action for the player is to get his head down in an attempt to impress the manager and hope a goal rekindles the spark that once made him one of the most feared operators in the Premier League.