Several Manchester United stars are said to be unhappy about training during the week.
Several key players, per the Manchester Evening News, are concerned about manager Erik ten Hag's grueling training regime.
Ten Hag often works his players into the ground to get them ready for matches.
However, many United players believe that after a tough last season and so many injuries, they need a change in approach.
United have been rocked by absences all season, with Marcus Rashford and Jonny Evans coming off hurt in a 3-1 loss to Manchester City.
Post-game, Ten Hag said: "I had to take them both off.
"They fought to be part of this game but after 60 or 70 minutes we had to take them off and sub them.
"We're working on players returning and I think players will return in the coming weeks, especially after the international break.
"Hopefully Jonny Evans and Marcus Rashford are not too bad, that they recover and we can use them in the next game against Everton."