Manchester United players "got away with murder" and behaved "shamefully" towards sacked manager Jose Mourinho, says ex-Red Devils captain Roy Keane.
Keane said it was indicative of the behaviour of modern players, who he says are "very weak human beings".
Mourinho was sacked on Tuesday, with former striker Ole Gunnar Solskjaer appointed caretaker manager until the end of the season.
"You would fall out with these players," Keane told BBC Radio 5 live.
"Players who turn up overweight, do not train properly and are not producing... for some to down tools, shame on some of those players.
"I am not Mourinho's biggest fan, but I can't tolerate footballers who hide behind agents, their pals in the media - it is a bit of a joke."
Mourinho was sacked after two and a half years in charge, with United 19 points behind Premier League leaders Liverpool.
He was reported to have repeatedly fallen out with players, including record £89m signing Paul Pogba.
Former Republic of Ireland midfielder Keane, speaking to Adrian Chiles, added: "The players got away with murder. They hide behind the manager. They have thrown him under the bus."
Modern players 'hide behind girlfriend's dog'
Keane spent 13 seasons at Old Trafford, winning seven Premier League titles, four FA Cups and the Champions League.
The 47-year-old said: "I was a bit old-school. But I would call it not old-school, but good-school.
"Whatever has gone on at the club, when you go on the pitch - particularly at a big club like United - you go out and give your all, no excuses.
"This idea that these players are upset... it is not just United, but the modern player. They are not just weak players, but are very weak human beings. You cannot say a word to them.
"Players are quick to hide behind social media, their cars and their girlfriend's dog, the whole lot.
"I was very lucky with the dressing room I was in. There were good men, good leaders and characters, but that is in shortage in the game now.
"It would not have happened in our dressing room. We would not have tolerated lads not putting a shift in."
'Ole bringing back feel-good factor'
Solskjaer has been appointed until the end of the season, with Mike Phelan - who worked under legendary manager Sir Alex Ferguson - alongside him.
Sixth-placed United play Cardiff on Saturday (17:30 GMT), before games against Huddersfield, Bournemouth and Newcastle.
Keane thinks Solskjaer is a "good fit".
"The beauty for Ole is it is a case of getting these lads back on side and that includes Pogba and whatever has gone on in the past you have to move on," he said.
"Ole will get that feel-good factor back, Mike Phelan back in is a good move, Ole will be popular around the club and I think getting the players back on side will be the easiest part of the job.
"They wanted a change and that is easy for Ole, you'd expect him to win the next few games, try and close the gap on the top teams, go on an FA Cup run and try and beat Paris St-Germain [in the Champions League].
"It is a big challenge ahead, but in the short term I expect the players to react and win the next few matches they should be winning."
Keane added: "The feel-good factor will come back, but the problems are still there when they play the bigger games in the next few months. It is hard to cut the gap on Liverpool and City.
"But Ole will want to get the first game out of the way, a victory under his belt and no doubt a lot will be happy to see him back at the club, as he is such a decent guy."
Not writing off Mourinho yet
Mourinho took over in May 2016 and led United to League Cup and Europa League titles in his first season, and finished second in the league last season.
"It is amazing how quick people are to criticise," said Keane. "You listen to people in the last week and everyone says he has lost the plot - that is a load of nonsense. At least he won trophies at United, his CV is amazing.
"Don't write Mourinho off yet, I hope he comes back and does well."
Speaking about United since Ferguson retired in 2013, Keane added: "It is amazing how far they have gone back in terms of performance compared to Manchester City and Liverpool.
"Everyone knew it would be difficult when Fergie left, but they never thought for one second they would be 19 points behind City last season and more this year. I am shocked how far back they have gone."