Arsene Wenger admits he must shield teenager Calum Chambers from the burden of a central defensive role despite Arsenal’s ongoing injury problems at the back.

The 19-year-old, who was signed from Southampton last summer, has been suspended twice but has otherwise featured in all but one of the Gunners’ fixtures this season.

However, Wenger has opted to deploy right-back Mathieu Debuchy as an emergency centre-half in recent games – and he has signalled that policy will continue for Arsenal’s Boxing Day clash against QPR (kick-off 5.30pm).

“For a 19-year-old player he [Chambers] has played too many games,” said the Gunners boss. “After 15, 17 games you have to give them a breather, get them fresh and get back again.

“At the moment, to have that responsibility in every single game is a lot for players of that age. I put Debuchy in because he’s good in the air and [in the 3-2 defeat] at Stoke we suffered in the air.

“He’s a defender of experience and that experience can sometimes make a difference, whereas the defensive responsibility’s a bit less on the flank.”

Laurent Koscielny’s ongoing calf problem has meant that Chambers, left-back Nacho Monreal and Debuchy have all been pressed into service to partner Per Mertesacker in the heart of Arsenal’s defence.

The Gunners have conceded seven goals in their last four games and Wenger concedes that lack of continuity may have had an adverse effect on the German’s form as well.

However, he expects that situation to improve once Koscielny returns – and that could even be as soon as Sunday, when Arsenal travel to West Ham (3pm) for their second London derby of the Christmas programme.

“I believe he’s on the way up, Mertesacker,” added the Frenchman. “He had a difficult start to the season but he has been much sharper.

“When you look at the number of players who have played centre-back this season, it’s not easy for him. When Koscielny comes back I think we’ll be more stable.

“We have had a depleted squad since the start of the season and no stability. The fact that we got so many important injuries at the back cost us – we lost Debuchy and Koscielny during the same period of three months. It’s too much.”

Club captain Mikel Arteta remains sidelined until the new year with an ankle injury, but Tomas Rosicky, Yaya Sanogo and goalkeeper David Ospina are all available again.