Laurent Koscielny is out of the weekend clash against Hull City leaving Arsenal with a major defensive crisis.

Koscielny is suffering with an achilles injury and will join Mathieu Debuchy on the sidelines.

The Gunners are already short of defensive cover and Koscielny's absence is a big blow.

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Arsenal defender Laurent Koscielny (right) got injured while on international duty with France this week

'He has an achilles problem, which has got worse,' said Wenger. 'He finds it difficult to play with it at the moment.

'You can only trust what the players says, he does not feel ready to play and will not play on Saturday.

'An inflammation of an achilles tendon, if you wait for it to be better, it can be a short time.

Koscielny leaves a press conference last Tuesday ahead of France vs Portugal

Mathieu Debuchy last played for Arsenal on September 13 when they drew 2-2 with Manchester City

'If you want to get rid of it completely, it is long term. We will monitor him and as soon as he can take enough pain again he will play.'

Asked if Koscielny needed surgery, Wenger added: 'No. We have scanned him, there is no real deterioration of his achilles at all.

'It is just the pain of the inflammation.'

Arsene Wenger is facing a defensive injury crisis with Debuchy also ruled out

With Debuchy and Koscielny both out Wenger must make a decision whether to move Calum Chambers to centre back and bring in Hector Bellerin at right back, or he can play left back Nacho Monreal out of position alongside Per Mertesacker in the centre.

Good news for Arsenal fans is that Aaron Ramsey is set to be included for the midweek Champions League tie against Anderlecht.

'He will be back in full training on Monday and certainly in the squad for Wednesday,' said Wenger, who also confirmed Theo Walcott will play for the Under 21s on Friday night after nine months out with a knee injury.

Aaron Ramsey is set to return against Anderlecht next week after a month out with a thigh injury