Leeds United have completed the signing of Chesterfield defender Liam Cooper for an undisclosed fee.
The two clubs agreed a fee for the 22-year-old, believed to be for an initial £600,000, on Tuesday before the former Hull City centre-half passed a medical and agreed personal terms on Wednesday. He has put pen to paper on a three-year deal.
Leeds had two previous bids for Cooper rejected by Sky Bet League 1 side Chesterfield last month.
"Liam has lots of potential as a defender," Leeds head coach Dave Hockaday told the club's official website.
"He has a great left foot and bringing him to the club is great business."
Cooper came through Hull's academy and signed a two-and-a-half year contract with Chesterfield following an initial loan spell in January 2013.
He made 48 appearances for the Spireites last season as the Derbyshire club secured automatic promotion as League Two champions.
Cooper is the third new player signed by the club in the space of 24 hours following the arrival of former Southampton striker Billy Sharp, who has signed a two-year contract, and Italian defender Guiseppe Bellusci, on a season-long loan from Catania.