Former Birmingham manager Gary Rowett has revealed that the Blues passed up on an offer to sign Manchester United's Victor Lindelof because he didn't seem strong enough a player at the time.
The Swedish defender, who completed a £39.5m move to Old Trafford over the summer, is yet to establish himself as a regular under Jose Mourinho.
And Rowett, now in charge at Derby County, has told Sky Sports that he was approached by an agent and was offered the player during his Birmingham days.
He said: "About two or three years ago when we first went into Birmingham an agent called us and said we are trying to get some of our younger players out to expose them to different levels.
"We had a look at him (Lindelof) and put it to some of the staff, but it was ironic because they felt he wasn't probably quite tough enough.
"Then suddenly he's been touted around at £20m or £30m. So I think we made a mistake. To be fair he got straight back in the Benfica side very quickly and of course went from strength to strength."
Lindelof, 23, did not make the bench for United in three of their four Premier League matches this season, but played the full 90 minutes in a win against Basel in the Champions League, also starting against Burton in this week's Carabao Cup tie.