By Graeme Bailey Blackburn Rovers have a huge decision to make in January over the future of Ben Brereton Diaz, with a number of Premier League giants ready to make their move, 90min understands. The 23-year-old’s contract at Ewood Park expires at the end of the season and it’s understood that he has told the club’s hierarchy that he won’t be extending his stay. That means promotion chasing Blackburn must now decide whether they want Brereton Diaz to spearhead their Premier League promotion charge – before losing him on a free transfer at the end of the season – or sell up in January when they…