STEVE McClaren is expected to take over as Middlesbrough manager tomorrow after speaking for the first time about his decision to quit Manchester United.

The 40-year-old will move into Bryan Robson's hotseat at the Riverside Stadium after accepting he would never replace Sir Alex Ferguson at Old Trafford.

''I realised I was well down in the pecking order,'' McClaren said.

''Within the space of 24 hours I made the hardest and easiest choices I have ever made.

''People say that nobody in their right mind would leave Manchester United and 99 times out of a hundred that would be true.

''But I had reached a stage where I needed to take a change in direction and the chance to manage a terrific club like Middlesbrough provided it.''

McClaren reveals that Ferguson gave his seal of approval to the Boro move, in stark contrast to the time when Brian Kidd left the United No 2 post for Blackburn.

''Sir Alex was the first person I turned to for advice about the Middlesbrough job and he gave me his total backing,'' added McClaren.

''I have nothing but the highest regard for him.

"I couldn't begin to assess the value of working alongside him and seeing how he operates.

''His departure will be an incalculable loss to the game and to United in particular. I hope he goes out in a blaze of glory.''

McClaren also insisted that he was impressed by offers from West Ham and Southampton, but once meeting Boro chairman Steve Gibson there was only one decision he could make.

He said: ''I was impressed with what I heard when speaking to the chairmen at West Ham and Southampton.

''They represented tremendous opportunities for someone like me attempting to bridge the gap between coaching and management.

''But as soon as I spoke to Middlesbrough chairman Steve Gibson I knew it was the club for me.

''I am ambitious but I don't think I've come across anybody who combines Gibson's ambition with such enthusiasm, optimism and drive.

''Saying 'yes' to him was easy especially after seeing the infrastructure at the club; the fantastic set-up they have at their training headquarters and hearing all the plans for the future.''

McClaren admits it will be a wrench to leave Old Trafford, but is determined to make it as a top manager.

''I can only say that being involved at United was an even more unforgettable experience than I ever imagined it would be when the call came from Sir Alex two-and-a-half years ago,'' he added.

''I had served a great apprenticeship working with Jim Smith at Derby County, but felt it was the right time to move on, as I do now.

''I have to confess I was more than a little apprehensive about moving to Old Trafford.

''Taking over from a United legend such as Brian Kidd and coaching all those great players was an awesome proposition but it was too good an opportunity to pass up.

''And look what I would have missed out on if I hadn't gone for it - three successive Premiership titles, an FA Cup and that unforgettable night in Barcelona when the lads snatched the European Cup.''

He added: ''Of course, I'll miss the boss. Sir Alex thought I was good enough to take over from him at Manchester United - there can be no higher praise than that.

''At Middlesbrough, I hope to prove he was right.''

The move was welcomed by many Boro fans who see McClaren as the best man to replace Bryan Robson.

David Buckton, chairman of the official Middlesbrough supporters club, congratulated McClaren on leaving the Red Devils.

He said: "It's a brave move and he deserves a chance. It all depends who he brings with him and what he spends but it looks promising.

"I am sure quite a lot of supporters will be looking forward to him coming and most will be behind him.

"A lot of people liked Bryan Robson but when they get used to the change they will support him."

Ferguson supported McClaren's move north to the Riverside and Boro's fans are hoping that another former United old boy will restore the Teesside club's fortunes following the ending of the Robson era.

Supporters are also hoping the relationship between Sir Alex and McClaren will benefit the club.

Mr Buckton said: "If some of Alex Ferguson's managerial skills have rubbed off on McClaren it could be a very interesting time."