The Chile international forced his exit from the Emirates in January after threatening to wind down his contract and United beat eventual champions Manchester City to his signature after agreeing an eye-watering £500,000-a-week deal.
Sanchez has been unable to reproduce his best form since his switch to Old Trafford, however, scoring just three times in 23 appearances and was dropped for Saturdays defeat at West Ham.
Reports on Sunday claimed Mourinho had given the 29-year-old a dressing down in training earlier in the week and Sanchez was said to have been left stunned by his managers decision to omit him from the matchday squad.
The Daily Mirror report Sanchez held a lengthy conversation with his former Arsenal teammate Lucas Perez, who joined the Hammers in the summer, in the London Stadium tunnel and now feels he joined the wrong club.
Sanchez caused disharmony during the latter period of his Arsenal career, falling out with and criticising his teammates and he was said to have left nothing to the imagination with his antics on Saturday after learning of Mourinhos decision.
For many months people are asking for Martial, Martial, Martial, said Mourinho after the match, explaining his decision to axe Sanchez and hand the France international a rare Premier League start.
For many months people are saying Alexis Sanchez is not playing well enough. So this week was time to agree and to say, lets give a chance to Martial and lets leave Alexis out.
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