Laurent Koscielny
Laurent Koscielny is expected to be out for two more weeksReuters

Arsenal manager Arsene Wenger has revealed that the North London side are likely to sign a defender during the January transfer window, after centre-back Laurent Koscielny suffered another knock.

Having being out for a lengthy period with an Achilles injury, the French international sustained another calf problem on his return to action against Southampton earlier in the month, missing games against Stoke City, the Champions League victory over Galatasaray, and Saturday's 4-1 win over Newcastle.

With Nacho Monreal also out of action due to another injury and Calum Chambers suspended, Wenger was forced to deploy right-back Mathieu Debuchy in the heart of the defence, as the manager only had one first-team centre-back available to face Alan Pardews' side, in Per Mertesacker.

Speaking to BBC Sport after the win, Wenger confirmed he expects to buy another centre-back in January: "Well yes, with Koscielny we're a bit cautious and we need cover."

Asked about the injuries of both Koscielny and Aaron Ramsey Wenger added that they would both be out for a few weeks.

The Gunners secure an easy win over Newcastle thanks to braces from Santi Cazorla and Olivier Giroud.

"We can score goals and we showed that again tonight. Overall it was a dynamic game where defensively – despite the fact that we were depleted at the back – we were quite solid."

"Going forward we always looked dangerous. In the end, we won in a convincing way. We scored four goals and that was needed. The response was strong after the Stoke City game and let's go well over Christmas."

Asked about Giroud he added: "He's still not 100% there, but he gives a presence.

"He links up well, plays good one-twos and protects the ball well. When we have to kick the ball long because Newcastle closed down our centre-backs well, you always have a good chance to win the ball."