If Arsene Wenger didn't know it by now then the early stages of this season would have provided the wake-up call: he needs a new centre-back.
The recent injury sustained by Laurent Koscielny has left the Gunners in all sorts of problems and, whilst he and Per Mertesacker are dominant enough when both fit, something needs to give if Arsenal to be true title contenders.
For most people that means Wenger dipping into the transfer funds and consenting to spending a portion of his allowance on another able defender. When we say able we're not talking about a French youngster who promises to be good in five or six years time, we mean someone who can slot in immediately and form one half of a solid partnership.
Since the summer there's been plenty of speculation surrounding the subject. Thomas Vermaelen's exit was somewhat covered for by the arrival of the burgeoning Calum Chambers, but even so fans would be far happier to see an individual of the highest quality bought in the coming months.
But what sort of players should Wenger be looking at? How does he separate the pretenders from the contenders?
You rest your feet Arsene, we've done the hard part for you. Click on the 'begin slideshow' button below to see who makes our list for the top five defenders Arsenal need to sign.