Johan Djourou and Laurent Koscielny
Arsenal have suffered from a disease called "defensive crisis."
In recent years, Arsene Wenger's men have shown that their offense can be brilliant. However, their defense has been very inconsistent, and for some unknown reason, Wenger hasn't signed anyone, except for Finnish Carl Jenkinson from Charlton.
The Gunners' defenders have been very injury-prone; some of them not being able to play, forcing Wenger to play younger, more inexperienced defenders.
Others, like Thomas Vermaelen, haven't been able to play for ages, as the Belgian missed virtually the whole season due to his calf injury.
But it's not only injuries that pose the problems.
Arsenal defenders have also not held their composure in the past, collapsing in crucial moments of the match.
For example in April, when Arsenal hosted a match against Liverpool, it was 0-0, until five minutes into stoppage time, when van Persie scored on a penalty. It seemed certain that Arsenal would win this match.
Then, two minutes later, Liverpool equalised with a Dirk Kuyt penalty after bombarding Arsenal's goal. Though the penalty was unfair, it just showed how the defense allowed such attacks on their goal in key parts of the game.
To prevent things like these, here are five defenders that Arsene Wenger could potentially sign.
Christopher Samba is a big, tough center back; he's not the kind of player who gets pushed around a lot, like some of the Arsenal defenders. At 6' 4", he's very tall, and therefore poses as an aerial threat, another quality that Arsenal lacks.
Samba, who currently plays for Blackburn, has publicly said that he wants to leave for a bigger club:
"If a good opportunity arises, I want to seize it. It is necessary that the club understands that I want to go one step further. I hope they will not put a stick in the wheels. It's been four and a half years I have been at Blackburn and two years I have played in relegation battles."
And an opportunity has arisen, as Arsene Wenger has already shown great interest in Samba.
It is rumored that the Gunners have already made a 8 million pound bid.
Jose Enrique has been a potential transfer target for Arsenal, and he was heavily linked with the club. As Gael Clichy has already left for Manchester City, Jose Enrique seems a good replacement for the left-back position.
The 25-year-old Spaniard currently plays for Newcastle, but he has been linked with Barcelona, Arsenal, Liverpool, AC Milan and Bayern Munich.
According to the Daily Mail, if Barcelona made a 12 million pound bid for Jose Enrique, it would be "difficult to resist."
Hopefully for Wenger, Enrique wants to sign for the Gunners, as he is a very good left back.
Leighton Baines is at the same time a defender and a threat on offense. While being able to make solid tackles, the Everton left back can run forward, as well as cross the ball successfully (something that Arsenal struggled with at times).
Baines has been a potential target for a few English clubs, and it was rumored that all of the big four clubs were checking out his game.
However, I think that Arsenal is the top contender for the Englishman, and he will be great for Arsene Wenger, as Gael Clichy has just left for the Eastlands.
Per Mertesacker is an intimidating presence, standing at 6'6". He is a fantastic tackler, and a huge threat in the air.
He would be great for Arsenal because the Gunners often have trouble winning headers at the back. Mertesacker is also extremely tough, and doesn't have many injury problems.
The 26-year-old currently plays for Werder Bremen, and played a key role in Germany's road to the 2010 World Cup semifinals. Mertesacker has been linked with several clubs, including Liverpool, Arsenal and more.
Though Thomas Schaaf, Werder Bremen's manager, has said that he won't allow Mertesacker to move to Arsenal, you shouldn't rule out that tiny possibility.
Because if Arsenal manage to sign the German, expect things to change with the Gunners' defense.
Gary Cahill has been eyed by many teams, but Owen Coyle said that no one has made a formal bid for the center back as yet. Cahill, another strong and tough player, would also improve Arsenal's defense, and he is only 25 years old.
The Englishman would be a great pick for Wenger, as there seems that there is less competition for him as time goes by.