He targeted Toby Alderweireld and Harry Maguire – with Koulibaly, alongside players like Jerome Boateng and Milan Skriniar, also being reported as targets – in the summer but the club refused to grant him a central defender ahead of the new campaign.
And according to Castles, writing in a report for the Daily Record, Mourinho has identified Koulibaly – who enjoyed an excellent campaign with Napoli last season – as the defender he wants to sign in January to replace the old guard of central defenders he no longer trusts.
If there was ever a time to sign a central defender, it was the summer – just after United had finished second and reached an FA Cup final.
Now, with 12 league games gone and 21 goals conceded – giving United a negative goal difference – the problems feel too endemic all of a sudden. And the board, stingy over transfers at the best of times, will most likely want to avoid giving Mourinho any further backing when it seems likely he won’t be at the club this time next year.