MARTIN O'NEILL has been earmarked by chairman Freddy Shepherd as the ideal candidate to succeed Graeme Souness as Newcastle United boss.

A disillusioned Shepherd sent a letter to Souness yesterday morning to end a 17-month reign on Tyneside - as Wednesday night's catastrophic 3-0 defeat at Manchester City proved the final nail in the Scot's managerial coffin.

Academy director Glenn Roeder has been installed as caretaker boss until a suitable replacement can be found and he will be assisted on the training field by club talisman Alan Shearer.

But it is the long-term that Shepherd will turn his attentions to today, as he starts his search for the new man who he hopes will deliver the club's first trophy in 37 years.

O'Neill, the former Celtic boss also strongly linked with the England job, is the man who the Newcastle chairman would love to take over the reins and is the top target.

However, the Northern Irishman, who quit from his post at Parkhead last May, is still not in a position to accept any role as he cares for his wife, Geraldine, who has cancer.

Bolton boss Sam Allardyce, who turned down the St James' Park job before Souness was installed, still remains a viable alternative but Bolton would fight tooth and nail to keep their man whose name is also under consideration by the Football Association for the England post.

And Wigan boss Paul Jewell, whose credibility has reached new levels after successfully guiding the Latics to a remarkable first season in the Premiership, is another name likely to stay in the frame, particularly as he has a clause in his contract at the JJB Stadium.

England coach Sven Goran Eriksson and former Newcastle boss Kevin Keegan, who received plenty of backing at the bookmakers yesterday, are also two candidates sure to be in the frame if O'Neill fails to materialise.

The search has started in earnest after Shepherd's letter to Souness.

And winger Nolberto Solano last night revealed how the Newcastle playing staff had sensed Souness was preparing himself for the worst before hearing the news.

Solano, whose arrival on deadline day in August has proven to be Souness' last as the Magpies boss, believes the 52-year-old had received a warning after the recent defeat to Blackburn that the axe would fall if things didn't improve.

"I feel very, very sad for the manager. He brought me back to the club I love and I will always owe him that. He's a good man and doesn't deserve the bad luck he has had," said Solano, reflecting on an extensive injury list that has eased in recent weeks.

"I think he knew something would happen after the Manchester City game. But we turned up to training this morning and heard a rumour he had come to say goodbye.

"He knew his time was up and I think he felt some of the recent criticism had gone too far. But he knows football and he knows it's part of the game."

The sacking of Souness, after a run of form that has seen Newcastle take just one point from the last 18 on offer, has sparked Shepherd's search for the fifth manager of his chairmanship at St James' Park.

Shearer, Roeder's right-hand-man, is also one of the front-runners in the bookmakers' eyes to take over full-time, despite his inexperience.

And, for now and for the short-term at least, the task of guiding Newcastle out of their current crisis lies at the hands of the newly-formed Roeder-Shearer coaching team.

Solano insists the whole squad has to move on and focus on making sure the managerial duo ensure Premiership status is retained for the new campaign.

"In training we have talked about the need to respond in the right way and help the caretaker manager as much as we can," said Solano, who is hoping to help claim Newcastle's first league win since December 17 tomorrow against Portsmouth.

Roeder and Shearer's roles can only be for the short-term, as neither possess the UEFA Pro Licence coaching certificate that is needed for them to take over the reins of a Premiership team on a permanent basis.

Frank Clark, a former Newcastle centre-back and a vice-chairman of the League Managers' Association, said: "That can only persist for 12 weeks under Premier League regulations, because neither Glenn nor Alan has the UEFA Pro License qualification."

And, if he does oversee a successful revitalisation at St James', it seems unlikely Roeder, scarred from his experiences at West Ham when he was sacked shortly after his return from battling against a brain tumour, would want a return to full-time management.

Speaking recently to Northern Echo SPORT, he said: "My ambition is not to manage again.

"If I can produce first team players for Newcastle it will be the world I want."

And Roeder added last night: "All our thoughts and energies will be directed at beating Portsmouth. All we can do is gather ourselves on Friday morning and go and pick a team that is going to beat Portsmouth on Saturday.

"It won't be easy but we will lift the spirits and be very positive about the whole thing.