Boro Go Head-To-Head With Man Utd In Court!
Collett was awarded the £4.5 million by a judge after a civil hearing in Manchester last August.
The court heard that although he attempted a comeback, Collett, now 23, was unable to sustain the level required to be a professional and was ultimately forced to retire from the game.
Both Smith and Middlesbrough accepted liability in a case where both Manchester United manager Sir Alex Ferguson and captain Gary Neville spoke on behalf of Collett.
Sir Alex told Manchester High Court that Collett had an "outstanding chance" of progressing to the first team and enjoying a career in the game.
The court heard Collett could have earned more than £13,000 a week, and could have played until the age of 35.
But both Smith and the North East club are now appealing against the size of the award.
The appeal court hearing is due to begin later today at the Civil Courts of Justice in Manchester.