The Portuguese boss has seen his team stagnate after a positive start to the season, and they currently lie eight points off the Premier League summit.
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And according to a BBC report, he is less than happy with attitudes around Old Trafford.
Defenders Luke Shaw and Chris Smalling found themselves the targets of public criticism at the weekend, with Mourinho suggesting their late withdrawals through injury against Swansea betrayed a “lack of fight.”
“There is a difference between the brave, who want to play at any cost, and the ones for whom a little pain can make a difference,” he told reporters, while exhorting his players to “do anything” for the team.
Preseason planning and fitness are apparently the two areas Mourinho is keen on improving, although he is considering a thorough investigation into “all aspects of the first team,” according to the report.
An abortive tour of China before the campaign kicked off left the ex-Real Madrid and Chelsea man furious, while he has taken steps to revamp the club’s fitness regime which may be taken further.
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In turn the boss has found himself in the spotlight already this season for mostly negative reasons.
His treatment of Bastian Schweinsteiger, who had been banished from the first team, and under-used new signing Henrikh Mkhitaryan has raised eyebrows, while he was forced to watch United’s 3-1 win over Swansea from the stands after a touchline bust-up with Mark Clattenburg the previous week.