Arsenal have sold defender Krystian Bielik to Derby for a projected £10m.
The Gunners will receive an initial fee worth £7.5m from Derby for the 21-year-old.
Bielik spent last season on loan with Charlton, helping them secure promotion to the Championship via the play-off route.
He joined Arsenal from Legia Warsaw in 2015 for £2m, but has only made two senior appearances for the club since then.
Bielik said: “I’m glad I joined Derby. You have a great coach here. I’m looking forward to it a lot because I know I can learn a lot from the gaffer.
“I want to learn a lot from the manager because I think he can help me to improve myself.
“I can’t wait to join the lads on the pitch and I can’t wait for the first game.”
Follow Deadline Day on Sky Sports
It’s Transfer Deadline Day for the Premier League and Championship on Thursday, August 8 and Sky Sports will be bringing you all the latest news on who your club is signing.
- Done deals – summer 2019
- Premier League ins and outs by club
- When does the transfer window close?
Start your day with Deadline Day Breakfast (6am) ahead of a special Good Morning Transfers show (9am), with Deadline Day – The Countdown (4pm) taking you to the 5pm deadline. The Transfer Show – Deadline Day at 6pm will analyse the big moves before Deadline Day at Ten rounds up all the transfer headlines.