The talented winger started his career with the Red Devils, but left to join the London club last year after the club grew tired of his off-field antics.
He has since thrived at Upton Park, with Sam Allardyce having made the wide-man a key member of his first-team this season.
Important goals against the likes of Tottenham and a number of swashbuckling displays have led to speculation of an England call-up ahead of the World Cup, however the Irons are believed to be considering cutting Morrison loose next month.
Recent reports have revealed a series of complicated buy-out clauses in his contract, with a £10m cash deal or an £18m swoop with a series of instalments said to be enough for his services.
It has been suggested that West Ham may move to keep their man by offering him a new deal, but now speculation indicates that Sam Allardyce is willing to sell in order to fund multiple moves in the coming transfer window.
‘Big Sam’s’ side currently find themselves in the relegation zone, and are chasing a top class striker and defensive reinforcements in a bid to steer clear of the drop.
Morrison could be sacrificed to fund swoops for fresh talent, with the 20-year-old one of their more sellable assets.
United could move, with David Moyes known to be looking to add some flair and guile to his attacking set-up.