An infuriated Sir Alex Ferguson has lost the second of Manchester United's two supreme teenage talents in midfielder Paul Pogba, who has been lured to Juventus by the promise of £830,000 a season.

Ferguson had made public pleas to both Pogba and Ravel Morrison – another member of last season's Youth Cup-winning side described by Paul Scholes as United's best since the fabled side of 1992 – to put their careers before money but the 18-year-old French player has been undeterred and his departure this summer now means United will secure only around £300,000 "training compensation". The deal will also secure £1.6m commission for Pogba's agent, Mino Raiola. The agent's demands are understood to have been a particular sticking point in negotiations.

Manchester City, Milan and Arsenal had all been made aware of Pogba's possible availability and he is now unlikely to be involved in first-team training again at United, following his decision to disregard Ferguson's entreaties and leave. The relationship between manager and player had deteriorated badly in the past few weeks, with suggestions that a row with Ferguson had led to him being dropped from the squad to face Ajax at Old Trafford two weeks ago and forced to train with the reserves.

Raiola told The Independent last week that it was "a precarious situation" and "difficult at the moment. Manchester United want him. It is up to the boy to make some decisions." Asked if there were uncertainties about whether his future lay at United, Raiola said: "Not from our side but that is a question to ask Mr Ferguson."

Pogba's arrival at United was as contentious as his departure has proved to be. The club were cleared by Fifa to sign the then 16-year-old from Le Havre in October 2009, following accusations of poaching by the French club. Ferguson publicly warned Pogba before Christmas not to wreck his United chances, after Raiola was engaged to work on the contract discussions.

The Manchester City striker Mario Balotelli claims his club do not fear United in the battle for the Premier League title. The enigmatic 21-year-old, who also admitted that a visit to a strip club last week had been a "mistake", is confident City will finish above Ferguson's team.