For the first season in the last several, Arsenal fans do not need to worry about the integrity of their team's defense.
Per Mertesacker and Laurent Koscielny have forged a rock-solid partnership in the center of the Gunners' back four. Kieran Gibbs is rapidly becoming one of the best left-backs in the Premier League after putting his injury troubles behind him and Bacary Sagna has stormed back from a sluggish end to last season.
Yet if one looks hard enough, it is clear that some holes remain. Sagna is out of contract at the end of the season and there are only three true center-backs in the squad, rather than the usual four.
These are not glaring weaknesses, but January is the time to plug minor holes. Let's look at five ways Arsenal can shore up their back line when the transfer window reopens.