Mourinho is reportedly unhappy with United's medical department.

But, having succeeded Louis van Gaal in the summer, it is understood Mourinho has found the general culture at United falling short of his expectations.

Mourinho has won 23 trophies in spells at Porto, Chelsea, Inter Milan and Real Madrid.

The Portuguese publicly questioned defender Luke Shaw, 21, and Chris Smalling, 26, for missing Sunday's 3-1 win at Swansea with injuries, telling the media: "For the team, you have to do anything."

BBC Sport understands Mourinho, 53, is looking at every area in his remit, including travel, pre-season tour planning, fitness, sports science and the general make-up of his squad.

At the start of the season, the former Chelsea manager predicted United would compete for the Premier League title this season.

However, Sunday's victory over second-bottom Swansea was only their second win in their past eight Premier League games. They are in sixth place - eight points off leaders Liverpool.

In addition, Thursday's 2-1 defeat at Fenerbahce left them outside the qualification places in their Europa League group.

United have reached the last eight of the EFL Cup but Mourinho remains unhappy at various aspects of club life.

He also recently described living alone in a Manchester hotel and being pursued by photographers as a "bit of a disaster".

What are the issues?

Mourinho railed in public during a shambolic pre-season tour of China, when the planned match in Beijing against Manchester City was scrapped on the day of the game due to the dire nature of the pitch.

He brought his own fitness specialist, Carlos Lalin, into United's medical department as part of his backroom team, when he succeeded Van Gaal in the summer.

In addition, star striker Zlatan Ibrahimovic, who has been involved in every game since his arrival from Paris St-Germain, has been allowed to continue using his own physio, Dario Fort.

Now Mourinho is looking at the fitness regime as a whole.

So far this season, Mourinho has lost 10 players for a combined total of 30 matches, whereas in his first 11 Premier League matches with Chelsea last season, Mourinho was without six players for a total of 17 weeks.

The lack of appearances from Henrikh Mkhitaryan, for whom United paid Borussia Dortmund £26.3m, has dismayed some supporters, as has the United manager's decision to make Germany midfielder Bastian Schweinsteiger train on his own until the beginning of last week.

On Wednesday, Professional Footballers' Association chief Gordon Taylor said he was "disappointed" with Mourinho's public criticism of Shaw and Smalling.

(BBC)