Summary:
Arsenal defender Calum Chambers has caused a stir by training with the club in a shirt number five.

Full article:
By . Paul Collins . New Arsenal signing Calum Chambers sparked a Twitter storm when he was picture training with his Gunners team-mates in a No 5 shirt on Tuesday. Chambers - whose £16million signing from Southampton was confirmed on Monday - has joined up with Arsene Wenger’s squad at their training camp in Austria. Although it has been widely reported that Chambers will wear the No 21 shirt in his first season at Arsenal, the picture of him wearing No 5 has raised further questions over the future of Thomas Vermaelen. Scroll down for video . Storm: Calum Chambers caused a stir on Twitter by wearing the No 5 shirt in Arsenal training . VIDEO Chambers aims to emulate ex-Saints stars . New boss: Chambers talks to Arsenal manager Arsene Wenger in training . Doubt: The situation has left Thomas Vermaelen's Arsenal future in further doubt . Arsenal’s No 5 Vermaelen is still the club’s official captain but he is understood to be frustrated at a lack of playing time behind first-choice defensive pairing Laurent Koscielny and Per Mertesacker. Manchester United and Barcelona have both been monitoring the Belgian’s situation but no decision has been made on his future yet. Chambers spent most of last season playing right back for Southampton but Wenger believes the 6ft 1in 19-year-old has all the attributes to be converted into a centre back.