United have started the season in terrible form and have taken just three points from three games, putting them in 16th place in the Premier League.
The Independent reports one player this week privately told a friend that "training is so basic" and "lacking in creativity".
It is also added that Solskjaer is said to feel "insecure" at the moment regarding United's form and his position as manager.
In the next month United face crunch fixtures which could make or break Solskjaer's tenure as manager.
It is also reported that sources claim there is now a "malaise" around the squad, with belief levels dipping by the week.