Man United are reportedly afraid Alexis Sanchez will not settle at the club and flop like Angel Di Maria.
The Chilean superstar, 29, arrived from Arsenal on huge £505k-a-week wages in January but has failed to make an impact on the field.
And the Daily Mail claims Sanchez is an isolated figure at United – often seen eating alone in the canteen.
A club source is reported as saying: “He looks like someone who doesn’t want to be here.
“The whole thing doesn’t seem right and he looks like a lost boy. It was the same with Di Maria.”
Di Maria joined United for a British record £59.7million fee in 2014 but failed to adapt to life at Old Trafford.
And the Argie ace quit for Paris Saint-Germain in a cut-price £44m deal the following year.
Sanchez’s huge wages could make it difficult for United to land targets this summer as players try and land mega-money contracts.
And Marcos Rojo has revealed his reaction to the signing after a rivalry developed between the South Americans.
The 28-year-old explained: “Alexis is a great player but we didn’t used to get on out on the pitch.
“Every time we came up against one another, whether in internationals or when United played Arsenal, I would give him a good kicking and he did the same to me.
“On top of that, I used to insult him and he would reply in kind.
“So when I learned that he was going to join United I said, ‘Oh, hell, no!'”