Calum Chambers has emerged as a shock transfer target for crystal palace, according to Sky Sports.

The Arsenal central defender spent last season on loan at Middlesbrough, where he made 25 appearances for the Riverside Stadium outfit before returning to the Gunners. He is not currently with the North London side, who are on pre-season tour in Australia and China, as he featured for the England under-21s in the European Championships last month.

Despite becoming a regular fixture in relegated Boro’s back line, putting in some impressive performances across the campaign, he has come back to a congested Arsenal defence and could move across London to Palace for a reported £20 million, a profit on the player they signed from Southampton three years ago.

Palace dealing with defensive problem

The Selhurst Park outfit have already improved their defensive line-up, signing Jairo Riedewald for just under £8 million, per the Guardian, with new Palace manager Frank de Boer pinching him from his former club Ajax. The Eagles are also closing in on a move for Bruno Martins Indi, who spent last season at Stoke City before moving back to parent club Porto.

De Boer’s focus on shoring up his defence follows a season in which Palace let in 63 goals, 10 more than relegated Middlesbrough, as they conceded four goals in three matches last year, while also attempting to bring some youth to ageing back line.

Scott Dann and Damien Delaney are already on the wrong side of 30 and will be featuring less, while the likes of Riedewald and Chambers would freshen up a side that is already struggling with a lack of depth, as well as, being useful in their ability to play in various positions.

Why are Arsenal letting him go?

For a player that is only 22-years-old and impressed in the Premier League last season, it seems odd that the Gunners are letting him go, albeit for more than the £16 million they spent to sign him from Southampton three years ago.

However, the England international left on loan last season to gain experience and get game time under his belt, but returns with little hope of getting on the pitch once again.

The Gunners have primarily used Shkodran Mustafi and Laurent Koscielny in central defence over the past 12 months, while Rob Holding joined them to form a three-man defensive line and Per Mertesacker was drafted in for their FA Cup final victory over Chelsea.

With Gabriel Paulista also a back-up option while new signing Sead Kolasinac also able to play at centre-back, Chambers would be a long way down the pecking order and therefore a move away can only benefit his career, despite a good start at the Emirates Stadium. It represents a good deal for Arsenal as well, should they make a profit on a defender that would not even make the matchday squad.