Twenty-seven days since his relationship with Alex Ferguson was officially declared over, Roy Keane checked in at Celtic yesterday with a new grade-two crop and a typically blunt explanation for why he had been ushered out of Manchester United and what his new team-mates could look forward to. "I'm not in this game to be popular," he said.

There will be many at Old Trafford who can vouch for that, not least those players who were castigated in his banned MUTV interview of October 31st, but Keane was at pains to emphasise that he would not set out to cause divisions in Celtic's dressingroom. As if to illustrate the point, he made it clear he was not interested in taking the captaincy from Neil Lennon and said there had been a "lot of nonsense" written about his outbursts and misdemeanours.

"They've nothing to fear," he said of his new colleagues. "I'm very much a team player, despite some reports. I like playing hard, training hard, pushing myself, pushing the people I work with. In the modern day there seems to be a fault with that. But that's what I do. And I've never asked a team-mate to do something I wouldn't do myself. (laughing) I'm sure the other players will love me."

As Gordon Strachan eulogised about adding one of "the world's best competitors" to Celtic's payroll, Keane confirmed he had spoken at length to Real Madrid as well as Bolton Wanderers, West Bromwich Albion and Everton. Madrid's interest had sorely tempted him, with their sporting director Emilio Butragueno making a personal call to him on Tuesday. "Over the phone is not really my cup of tea," Keane explained, pointing out that he had had a two-hour meeting with Strachan in London a fortnight ago. "Madrid wanted to wait another week but I wasn't prepared to. He understood that and was very amicable."

Of the interest from the three Premiership clubs, he added: "They all handled themselves brilliantly. I was impressed by all their managers and I feel like I have let one or two down. But you can't please everybody, I learned that early in my career. There's no doubt in my mind I have made the right decision."

Keane did not go into the finer details of his departure from Old Trafford but he did confess that he had envisaged spending the rest of his career at the club. He also confirmed that, having recovered from a broken toe, Ferguson suddenly pulled him out a reserve game against Liverpool on November 17th. It was one of the defining moments in the breakdown of their relationship. "I was fit four weeks ago," said Keane, who will wear the number 16 shirt at Celtic. "It's been frustrating as I was up and running."

Without mentioning Ferguson by name, there were thinly disguised references to the man he once regarded as his mentor. "I push myself hard every day and I push my team-mates hard. People were quite happy with that until a few months ago but then things change and you have to move on. I had 12 happy years at Manchester United, a fantastic club. I was very lucky and the manager was great to me, but we'd come to the end. The relationship we had came to an end."

Keane has signed an 18-month contract and plans to complete his coaching qualifications next summer. Celtic's chief executive Peter Lawwel made it clear early in the press conference that Dermot Desmond, the club's majority shareholder, had not financed any part of the deal. Strachan also had a point to make, reacting angrily over rumours the board had sanctioned the transfer without his authority. "It was too good an opportunity to turn down," he insisted.

Keane will register as a player on January 1st but the Scottish Football Association's rules dictate he will have to wait a week before making his debut, in a Scottish Cup third-round tie at Clyde's 8,200-capacity Broadwood stadium. It is a modest setting, but Keane is desperate to get back playing.

"People seem to think I'm 94 when I'm actually 34. The medical went well, believe it or not. I've not come here on a PR trip or an ego trip, for financial reasons or to unwind, far from it. I'm here to win matches and help the squad. I know I'm still a decent player and that I've got something to offer."