The 19-year-old defender joined the Londoners for £16 million from Premier League rivals Southampton in July and has made an encouraging start to his Gunners career.
Manager Arsene Wenger hailed the teenager as "outstanding" in the Community Shield victory over Manchester City on Sunday and expects him to challenge Per Mertesacker and Laurent Koscielny for a starting berth at centre-back following Thomas Vermaelen's move to Barcelona.
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"He's a really good lad and everyone really likes him - the boys really want to go out of their way to help him bed in.
"We saw him play for Arsenal for the first time at the Emirates Cup and I thought he was superb for a 19-year-old playing centre-back against really good players. I thought he looked very assured and he's going to be a great talent for the club.
"It's really good to see him here. It's almost weird because I can remember being in his position a few years ago - coming from Southampton to a big club like Arsenal - even though Southampton is a big club.
"But to come to a team like Arsenal, he's playing with players like Mesut Ozil and Alexis Sanchez. When you move to a team like Arsenal it's very surprising to start off with but he has settled in really quickly and all the boys love him.
"He's already trying to look after me, he's on the pitch trying to tell me to switch on and that's a really good sign because it shows he's feeling confident and comfortable and that's what we like to see. He seems like he's enjoying himself so I think he's going to have a good time here."