Birmingham have agreed a fee with Barnsley for defender Marc Roberts, Press Association Sport understands.
Barnsley boss Paul Heckingbottom revealed on Thursday that the Tykes had turned down bids for their captain from two Sky Bet Championship rivals, with one of those clubs thought to be Birmingham.
But Blues have now met Barnsley's valuation of the player, thought to be in the region of £3.5million, although the total value of the deal could rise with add-ons and clauses and the 26-year-old could see his move to St Andrew's completed over the weekend.
Birmingham's move for Roberts suggests Harry Redknapp has conceded defeat in his attempt to sign former England and Chelsea captain John Terry.
Redknapp had offered Terry a contract at Blues but it looks likely the 36-year-old, who officially becomes a free agent on Saturday when his contract at Chelsea expires, will sign for Birmingham's city rivals Aston Villa.
Roberts, who has a year remaining on the contract he signed at Oakwell in 2015 when joining the club from non-league Halifax, is a defender in the same mould as Terry.
During his first season with Barnsley he played a major role in helping them win promotion from League One via the play-offs and after only one season in the Championship he has quickly carved out a reputation as one of the best centre-halves in the division.
Meanwhile, Barnsley should prepare themselves to receive an offer for another of their players with Press Association Sport also understanding that QPR are expected to firm up their interest in Andy Yiadom with an actual bid for the full-back.
