To be fair to Arsenal, you've got to feel for them. Just a little bit.

Whilst Arsene Wenger has gone about his transfer waiting game in typical fashion, the camp were hit with the devastating news that defender Per Mertesacker will be out for "months" with a knee injury.

The defender is hardly a Gunners favourite but he offers a certain amount of defensive stability and leadership in the back-four, and his injury means Wenger has no choice but to search for a replacement.

Gabriel, Laurent Koscielny and Calum Chambers are left at the Emirates, but with the Brazilian struggling to adapt to the pace of the Premier League and Chambers struggling to break into the side, the time has come for a bit of Arsene Wenger ambition.

It's hardly the most exciting position to have to fill but Gunners fans will be hoping to see a replacement good enough to step-up and even make the position their own for the long-term.

With Granit Xhaka, Rob Holding and Takuma Asano the only names to have been brought to the Emirates this summer, the thought is that Arsenal really need to get busy sometime soon and can start with an imminent arrival to replace the unlucky German.

So with this in mind, who should Arsene be targeting?

Here's THREE established centre-back who could really relieve Arsenal's defensive woes.

Marquinhos

Marquinhos 1

Whilst he may not be a player that instantly springs to mind, there is little doubt that Brazilian international Marquinhos could tick a number of boxes for the Gunners.

After signing for Paris Saint-Germain for €31.4 million back in 2013, he's won over ten trophies during his stay in France. He's had to play second fiddle after fellow countryman David Luiz was acquired by the club, but he is still considered as one of the best young defenders in the game and made over 40 appearances for PSG last season.

He's extremely competent in his defensive game and has an excellent ability to read the game, with former Roma defender Nicolas Burdisso once describing him as "A little phenomenon who has speed, heading ability and is humble. He is a little Thiago Silva". Not a bad comparison to draw at all.

Javi Martinez

Javi Martinez

Perhaps a more astute replacement, there is little doubting Javi Martinez's quality at the top level.

Whilst he has found game a little more difficult to come by at Bayern Munich over the past couple of seasons due to incredibly competitive competition, he still made over 25 appearances for the first-team last time out.

He'd bring a wealth of experience that has seen him win an array of trophies over the past five years alone, including four league titles, two German Cups, One Champions League a World Cup and a European Championship medal.

Some CV, eh?

Aymeric Laporte

Aymeric Laporte

One of the most exciting and talented young defenders in Europe, Aymeric Laporte is considered the cream of the crop when it comes to Athletic Bilbao's current team.

He's been intensively linked with a move to Manchester City this summer, and it would prove a real coup if the Gunners could jump in and hijack a move for one of Europe's best.

On the pitch, he's a real leader, even at just 22 years-old. Great in the air with good awareness, he helped Bilbao to a fifth placed finish last season, missing out on the top-four by just four points.

There is little doubt this talented young man will move onto bigger and better things at some point in his career, but could it be sooner rather than later? He'd cost an arm and a leg but he'd bring real quality to the Emirates.