Where would Arsenal be without their crafty Laurent Koscielny? He's been one of the standout defenders in the Premier League for over five years now, but is he the best?
He moved to the Gunners from FC Lorient for an £8.5 million fee in 2010, which is regarded as one of the best pieces of business in the modern era.
The Frenchman was quoted by The Sun recently that he could have moved away from the north London club.
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He said: "There were teams interested in me but I always asked myself if it was worth taking the risk.
“I’ve seen a good few players leave for a bigger club and find themselves on the substitutes’ bench."
Signed at 24-years-old, Arsene Wenger bought a player heading into his peak years, and he has been considerably rewarded.
Racking-up 231 appearances for his club, during his five year spell, and 11 clean sheets this season alone, Koscielny continues to receive the plaudits.
The Frenchman has played an integral part in ensuring Champions League football is played at the Emirates year on year, as well as winning back-to-back FA Cups.
He's even chipped in with 19 goals for the club, including a crucial equaliser against Hull at Wembley in 2014.
Needs big game improvement
Where the former Lorient defender could improve is in big matches. Often error-prone in the tough away games, his side shipped four goals against St Mary's, three at Anfield, two at Chelsea and five at the Allianz Arena. All of which isn't particularly good reading.
He's also been known to score a few own goals, most notably when he stuck the ball in his own net at Anfield in 2012. To be fair to the French international, he hasn't scored an own-goal since that year.
It's not entirely his fault that big games pose a problem either. Wenger's side are known to have found it tricky playing against the top teams, with most of the criticism aimed at the way in which the manager sets-up his side.
Only until Francis Coquelin's emergence have they started to put that right, as he's given Koscielny some much-needed protection.
Could do with a better partner
One thing that lets the Arsenal centre-half down, is his partner Per Mertesacker. The German lacks pace, and is frequently out of position, leaving the Gunners exposed.
If Koscielny were to have a reliable colleague alongside him, his performances in the big matches could significantly improve.
The players the Frenchman is competing against are north London rivals, Toby Alderweireld and Jan Vertonghen. These two have formed a formidable partnership this season, and because Koscielny doesn't have a sturdy partner in defence, some will say this puts the Tottenham duo ahead of him in the rankings.
Vincent Kompany is normally known as the best centre-back in the Premier League. However, with the Belgian constantly picking up new injuries, Koscielny has probably stepped ahead of him.
John Terry was regarded as the best defender in the league last season as he led his Chelsea side to the league title, but his form has derailed, alongside his club's league position.
Others will say Robert Huth and Wes Morgan deserve a mention, for the way in which they have helped lift Leicester to top of the table.
Even though it has to be said that their form has been nothing short of remarkable, playing for a club like Leicester as opposed to one of the Premier League's juggernauts, possesses a heavy-burden of pressure.
Chris Smalling has also shown signs that England could rely on him in the future, but when Louis van Gaal, lets his side have more freedom, he has been often found out.
John Stones is certainly up there, incredibly composed and one of the most sought after defenders in Europe.
Koscielny is everything you want in a defender, he is quick, reads the game superbly, and is dominant in the air. Like Stones though, without having a dependable partner alongside him, Koscielny is often unprotected and prone to mistakes.
Alderweireld and Vertonghen look to be the most consistent defenders in the Premier League at the moment, but need to prove they can do it until the end of the season. If they can, then they could arguably be the best.
If the Arsenal defender can lead the Gunners to the title, then that would put the doubters to bed, and he will surely be seen as the best defender then.
To judge it overall though, it will probably be who holds their nerve the best between the north London trio come the end of the season.
Who is the best centre-back in the Premier League? Have YOUR say in the comment box below!