Derby have signed Poland Under-21 international Krystian Bielik from Arsenal.

The reported £9.5m sum paid for the versatile defensive player, including add-ons in the deal, would become a club record for the Rams, to eclipse the £8m spent on signing striker Matej Vydra from Watford in 2016.

Bielik, who impressed during a loan spell at Charlton in League One last season, has agreed a five-year contract and could make his debut at Huddersfield on Monday. He joined Arsenal in 2015 but leaves the London club having failed to make a Premier League appearance.

“We’re very happy. 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,” Derby boss Phillip Cocu said. “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.”

Bielik, who can play as a centre-back or a defensive midfielder, becomes the fourth new arrival at Derby this summer, following Graeme Shinnie, Kieran Dowell and Matt Clarke to Pride Park.

On Friday, the Rams also completed a season-long loan deal for Brighton centre-half Clarke. The 22-year-old joined Brighton from Portsmouth on a four-year deal earlier this summer for a reported fee of £3.5m, becoming Graham Potter’s first signing as Albion boss.

However, Potter sees the best way for him to continue his development is in the Championship with the Rams. Clarke too could be in contention to make his debut in Derby’s Championship opener at Huddersfield.

Reece Oxford made his final West Ham appearance in a pre-season friendly at Dagenham & Redbridge. Photograph: TGSPhoto/Rex/Shutterstock

Oxford leaves West Ham for Augsburg

Reece Oxford has left West Ham to join Bundesliga side Augsburg permanently after a successful loan spell.

The defender, who can also play in central midfield, became West Ham’s youngest ever first-team player in 2015, playing in the Europa League at the age of 16. Oxford failed to break into the first team regularly, and now departs for an undisclosed fee.

“I’m delighted to have joined Augsburg on a permanent basis,” he said. “I felt very comfortable in the city during my loan spell last season and would like to take the next step in my development here.”

Oxford, who also had loan spells at Reading and Borussia Monchengladbach, has signed a four-year contract, ending an eight-year spell at the London club. “The education I’ve received at West Ham has set me up,” Oxford added. “I’ve learnt a lot and I’ll never forget it.”

Elsewhere, Sheffield United have completed the club-record signing of Swansea forward Oli McBurnie after agreeing an initial £18m fee on Wednesday. Burnley have bolstered their goalkeeping ranks after Tom Heaton’s departure, with Leeds keeper Bailey Peacock-Farrell moving to Turf Moor for a reported £3m.