Highly-rated Tranmere winger Steve Davies has signed for Derby on a three-year contract.
Davies, 20, is out of contract at Prenton Park but, due to his age, Rovers will be entitled to a fee.
The Rams have had an offer rejected by the League One club but the player's registration will be confirmed and the transfer completed by tribunal if the two clubs cannot reach an agreement.
A statement on Derby's official website said: "Derby County are delighted to confirm the signing of Steve Davies on a three-year contract from Tranmere Rovers.
"The club has made an offer to Tranmere for the 20-year-old forward, however that has been rejected. Davies is out of contract but under the age of 24, so subject to a tribunal if a fee cannot be agreed.
"Derby County hope to continue negotiations with the League One club, however, the player's registration will be confirmed and the transfer completed by tribunal if necessary."