Arsenal have put a new central defender on their summer shopping list, throwing Per Mertesacker's role at the club into doubt. Gunners scouts have been instructed to identify potential central defensive targets this summer, despite the fact Gabriel only arrived from Villarreal in January. Borussia Dortmund's Neven Subotic has been scouted in recent months, while Aleksandar Dragovic is also on the club's radar. Per Mertesacker impressed in Arsenal's victory at Manchester United in the FA Cup on Monday evening . The World Cup winner, pictured celebrating with Aaron Ramsey, has been criticised this season . Gabriel and Laurent Koscielny's place in Arsene Wenger's plans for next season look secure. But the arrival of a new centre back in the summer is likely to have repercussions for Mertesacker. The German's performance have been criticised this season, though he was excellent in Monday's euphoric FA Cup win over Manchester United. Borussia Dortmund defender Neven Subotic has been scouted in recent months by Arsenal . Aleksandar Dragovic, pictured in action for Dynamo Kiev, has also been targeted by the Gunners . He was recently dropped by Wenger, but Gabriel's hamstring injury has seen the defender handed an instant route back into the first-team. And the arrival of a new centre-half could marginalise Mertesacker's role in Wenger's plans. The capture of a new central defender could also have consequences for Calum Chambers. The England international has been used as cover at centre-back this season, but the club's transfer plans could mean Wenger sees his long-term future at right-back or holding midfield.
Arsene Wenger has put a new defender at the top of his shopping list . Neven Subotic and  Aleksandar Dragovic are both on the club's radar . It could have repercussions for World Cup winner Per Mertesacker . The German has been criticised this season although he impressed in Arsenal's FA Cup victory against Manchester United at Old Trafford . CLICK HERE for all the latest Arsenal news .