Derby County have confirmed the signing of Krystian Bielik from Arsenal.
The 21-year-old, who impressed at this summer's European Championships, spent last season on loan at Charlton Athletic and helped them earn promotion to the Championship.
He has signed a five-year deal with the Rams and new manager Phillip Cocu is delighted with the transfer.
"He is a young player at the age of 21 and it is a permanent deal which I think is a very good investment for the club," Cocu told dcfc.co.uk .
"I am very happy he has joined the team.
"He will get better and develop, but for his age he is a very good player."
The fee taking Bielik to Pride Park is undisclosed.
Although, the Derby Telegraph have reported that the initial fee is under the Rams ' previous transfer record of £8m - paid to Watford for Matej Vydra three years ago - add-ons and clauses could push the amount for Bielik towards the £10m mark.
This is great news for Unai Emery as he looks to complete a deal for Celtic left-back Kieran Tierney.
It's no secret that Emery would like to improve his defence ahead of the upcoming season and the focus could now shift to the Scotland international.
The 22-year-old has been the subject of intense speculation, with the Scottish Champions holding firm over one of their star players.
According to the Scottish Daily Mail an agreement between Arsenal and Celtic is set to be confirmed ahead of the Hoops' Champions League first leg tie against Romanian side Cluj on August 7.
Could it be that this windfall from Bielik's sale to Derby County is what finally triggers Tierney's move to the Emirates Stadium?
Alternatively, the Gunners could use the extra funds and put it towards a bid for a new centre-back.
