Arsenal head coach Unai Emery admits he may be forced to add a central defender to his January shopping list.
The Gunners are without a host of defenders and look like heading to Southampton on Sunday with only one fit centre-back, in the shape of the recently returned Laurent Koscielny.
The club captain has been missing since May with an Achilles injury, although Emery says the 33-year-old is due to start Thursday's Europa League match at home to Qarabag.
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If Koscielny comes through that, he is likely to be in the line-up at St Mary's, with Konstantinos Mavropanos and Rob Holding injured, Shkodran Mustafi struggling with a hamstring problem, and Sokratis Papastathopoulos suspended.
Chelsea's Gary Cahill and Eric Bailly of Manchester United have recently been linked with a move to the Emirates and Emery said: "I think if we can take one player to help us at centre-back, I think it's a good option.
"The transfer (window) is not easy. Koscielny is coming back and for the team it's very important he is coming back.
"Then we are going to wait and see how Mavropanos is improving with his injuries, because he is also a centre-back who can help us.
"Another option we can play with two, with three, and (full-backs) Nacho Monreal and (Stephan) Lichtsteiner can play in this position.
"I prefer to use, if we can, a specialist centre-back."