That’s according to former Ireland team-mate Clinton Morrison.
Keane made headlines at the 2002 World Cup when he left the tournament.
The Irishman had a falling out with Mick McCarthy over an interview given to the Irish Times about the training conditions.
The United legend was joined in the squad by Morrison, who was in his early 20s at the time.
And he told talkSPORT what it was like to be in the room when the row first started.
Speaking to Jim White, the 39-year-old said: “We always have a singsong, so I was there singing, but then Mick came in with a paper.
“I remember it because I was sat there. Steve Finnan was sat between me and Roy.
“Mick said ‘I told everyone not to do any interviews. Why have you done this?’”
This latest insight into Keane’s fallout comes as:
“But Roy said ‘I did an interview because I wanted to do an interview.
“‘It’s not been good enough here, the set up and the surroundings.’
“So Mick said he was out of order but Roy replied ’I don’t care’ and they started arguing.”
Keane’s former team-mate then revealed that the United legend almost turned on his own players.
“I’m thinking our best player that Ireland have produced for many, many years is there arguing with Mick,” Morrison added.
“Most people born in England put their heads down, thinking ‘please don’t come for me either”
“The whole squad was watching. He said ‘You were a bad player.
“‘You had a rubbish first touch and you’re a poor manager.
“‘The only manager I respect is Sir Alex Ferguson.’
“Then he said ‘you’re English, you’re not even Irish’.
“As soon as he said that, most people born in England put their heads down, thinking ‘please don’t come for me either’.”
The 39-year-old was almost witness to a fracas between the pair.
Morrison continued: “They were firing insults and I could see Mick slowly coming round.
“It would never have gone to blows but Roy was steaming.
“I think Mick could have done it differently, going to see him one-on-one. Roy was always fighting.
“It was separated by the assistant manager and Roy said ‘what are you going to do?’”
And Morrison also said how the midfielder nearly came back to Korea.
“He had to send him home,” the former Crystal Palace said.
“Within two days, Roy was back in Manchester wearing that horrendous Diadora tracksuit walking his dog.
“He was going to come back but we missed the cut off date.
“They called in another player but he was injured.
“We missed him.”
It comes as Keane, currently assistant manager at Nottingham Forest, had a bust-up with Aston Villa’s John Terry.