'He ruled by fear,' one source close to the squad told The Telegraph. He said that Keane's hardline management methods had alienated many at the relegation-threatened football club.

Keane dropped summer signings Djibril Cisse and El-Hadji Diouf for the match against Chelsea on Nov 1 - when Sunderland lost 0-5.

He disciplined them for attending Obafemi Martins' birthday party in Newcastle two nights before.

His relationship with another big buy, Pascal Chimbonda, part of a £15 million (S$34 million) deal with Spurs for Teemu Tainio and Steed Malbranque, had also deteriorated to breaking point.

And while few, if any, rival midfielders Keane faced during a distinguished playing career would even dream of associating the Irishman with cowardice, his failure to turn up for training even once this week tells another, vastly different, story.

So, too, did his method for telling Sunderland chairman Niall Quinn that he was quitting. He delivered that by text message.

The headlines in the newspapers made for grim reading.

'When the going got tough, the manager went missing', wrote The Guardian, sharing a similar theme with The Times. 'When the going got tough, Keane got going,' the latter reported.

The Independent had a piece entitled: 'Keane - The fighter who quit when most needed.'

Pundit Tony Cascarino believes his former Republic of Ireland teammate will never be given a job again - for the way he left a team, whom he steered to promotion in 2006, mired in relegation after spending nearly £80 million on 34 signings.

He told talkSport: 'Keane's taken the easy option. He's not rolled up his sleeves and, even with as much courage as he says he's got, this is the end for him.

'He'll not manage again. No one will give him the opportunity to manage a football club because they won't trust him. That's the bottom line.

'You're going to have bad results in your management career as you do in your playing career. But you don't just walk away.'

Cascarino also questioned whether Keane was ever cut out for management, given what he described as his 'insular' nature.

United manager Alex Ferguson, who should know the controversial Keane better than most, said: 'It's difficult to say whether he will be back or not. He was an incredibly controversial character.'

Keane, who did his work without an assistant manager or proper scouts, did not help his own cause with a series of bad buys in the market.

Craig Gordon, the £9 million Scottish goalkeeper, has failed to convince. Anton Ferdinand cost £8million from West Ham, more than United paid for Nemanja Vidic and Liverpool for Martin Skrtel.

'History suggests I've not been great at dealing with setbacks,' Keane admitted early last season. It proved a prophetic reflection from the 37-year-old.

AGENCE FRANCE-PRESSE