Sir Alex Ferguson must have had a fair amount of time on his hands to watch football since stepping down as manager of Manchester United at the end of last season, but you could forgive him if he actively avoids any match involving Juventus or France.
The reason? Paul Pogba, the gifted young midfielder Ferguson allowed to slip away from Manchester United in 2012, is now a key player for both.
The Scot and all the coaches at Old Trafford knew exactly how talented the Frenchman was, but their failure to hand him first-team opportunities naturally led to increased frustration, which eventually prompted his decision to join Juventus when a lucrative offer came through from the Italian giants.
Pogba made it clear to Ferguson that he would not sign a contract extension unless he featured on a more regular basis for the Red Devils.
He knew that he was ready to start matches, but during the 2011/12 campaign he made just three Premier League appearances, plus a handful in the League Cup and one in Europe.
For a player as talented and self-assured as Pogba, this simply was not good enough. There have been numerous examples of players under the age of 20 establishing themselves in the first teams of the world's top clubs - but in the end Pogba became one of the latest at the Juventus Stadium rather than Old Trafford.
Ferguson often cites the sale of Jaap Stam to Lazio as one of the biggest mistake of his managerial career; however, at least United got two-and-a-half excellent years out of the rock-solid former Netherlands defender.
Out of Pogba they got nothing - except the FA Youth Cup.
The 20-year-old is now a vital player for Juventus and France, with whom he could go to Brazil next summer for the 2014 World Cup finals and further enhance his burgeoning reputation.
He is likely to have another 15-20 years at the very top level - and there will always be a question of 'what if?' in the minds of the Manchester United faithful.
Pogba is the player the Red Devils are currently crying out for: a big, physical presence in midfield who can also arrive in the box late and score goals.
For the sake of £30,000-a-week and a few more games in the first team, Ferguson cost United a world-class player.
But lessons of the past appear to have been heeded by Ferguson's successor David Moyes, who made no such mistakes with Adnan Januzaj this season.