Roy Keane has said that many of the current Manchester United players are "cry babies" who are not playing for their pride.
The club has suffered an uncomfortable start to the season, going out of the Carabao Cup at home against Championship side Derby and are in the midst of their worst start to a league campaign in 29 years after last weekend's 3-1 defeat at West Ham.
Their goalless draw in the Champions League against Valencia means United are without a win in four successive home games, the first time that has happened to Jose Mourinho in his managerial career.
The Republic of Ireland assistant manager has chosen to criticise the performance of the players rather than United boss Jose Mourinho, and he aimed his barb at other players aside from Paul Pogba.
When asked about the current situation at Manchester United, the Ireland assistant coach told Notts TV that some players can't take criticism.
He said: "I'm not talking about Pogba. I'm talking about players in general. Players who get upset with a manager or a coaching staff and think 'I'm not going to train properly because somebody upset me'.
"When you walk out on that pitch you're playing for your pride, you're playing for your family, you're playing for your city, whatever it might be.
"Don't get that worried about what the manager's said about you, or the coaching staff, you get out there and play.
"You can follow it up after the match but when the game's going on liven up. Play with pride, play with energy, play with spirit.
"Hopefully play with a bit of skill. But on your bad days you roll your sleeves up and you fight for that jersey. Don't get distracted by the balloons out there."
Keane said arguments amongst teammates happen all the time and players have to rise above them when they get onto the pitch.
The former Man Utd midfielder said: "You talk about footballers and managers, not every player is going to get on with their manager and not every manager is going to like every player.
"But what you do as a footballer, and I've had one or two disagreements, when you cross that line you play for your team.
"Unfortunately when you're Man United, one of the biggest clubs in the world, things will get exaggerated.
"And if you're a footballer for Manchester United, you put that jersey on, you walk out and you don't give 100% because you might be upset with somebody then good luck to Mourinho with this stuff."
- Digital Desk