Manchester United are concerned that Alexis Sanchez is struggling to settle at the club and fear a repeat of the Angel Di Maria fiasco.
Sanchez became the highest-paid player in the Premier League on a total of £600,000 a week when United gazumped rivals Manchester City to sign him from Arsenal in January.
However, the 29-year-old's disappointing form has produced only one goal in 10 games and he was on the bench for the first time when Jose Mourinho's side beat Brighton in the FA Cup last Saturday.
Sanchez, who is preparing with the Chile squad for their internationals against Sweden and Denmark, has a reputation for being single-minded and sullen at times.