The 29-year-old completed a high-profile switch to Old Trafford from Premier League rivals Arsenal in January to much fanfare among the United faithful.
However, Sanchez has scored just one goal in 10 appearances and was overlooked for selection in the 2-0 win over Brighton & Hove Albion in the quarter-finals of the FA Cup.
According to The Sun, several United players confronted Sanchez at half time during the Champions League second-leg defeat at home to Sevilla.
The report claims that the Chilean's failure to track back, his workrate when the team had lost the ball and his reluctance to cover for out-of-position teammates saw him admonished.
Sanchez's purported response was to shrug his shoulders, and the fear at Carrington, according to the newspaper, is that the forward's tenure at the club will be similar to that of Angel Di Maria.
The former Barcelona star enjoyed a fruitful spell at Arsenal, scoring 80 goals and registering 46 assists in 166 games.