Sir Alex Ferguson brought 13 league titles, five FA Cups and two Champions League triumphs to Manchester United in a glorious 26-year reign as manager.
His impact on the club is invaluable but even managers as good as Fergie don't turn everything they touch into gold. Their mistakes can even sometimes cost the best part of £90m.
Ferguson allowed a young Paul Pogba to run down his contract at United and leave for Juventus, with just £800,000 returned in compensation.
Fast-forward four years and United have forked out roughly £90m — a world record fee — to bring him back to Old Trafford.
The above chart demonstrates how badly that huge mark-up compares to other players who have returned to the their first senior club.
The best deal belongs to the canny Atletico Madrid, who sold local hero Fernando Torres for just over £30m in 2007 and took him back on a free transfer nine years later after having him two seasons on loan.
Nonetheless, United are on course to be named the richest club in world football this year while Pogba himself has massively improved during his spell in Italy.
With an expected £500m entering the club coffers this year, it's doubtful United will be losing too much sleep over this one.