N'Koulou, 24, arrived in France back in 2007 from Kadji Sports Academy in his native Cameroon, signing for Monaco as a 17-year-old. During a three-and-a-half year stay with the club, N'Koulou established himself as a key member of the team, making 78 appearances before his displays attracted interest from Marseille, who swooped to sign him in 2011.
A €3.5m capture for Marseille boss Didier Deschamps, N'Koulou became a key player at centre back, despite having featured heavily in midfield for Monaco previously. His displays in defense even led to his inclusion in the Ligue 1 team of the year in 2012, and he has continued that high standard throughout his spell at the Stade Velodrome.
But Marseille are currently struggling financially, and whilst interest is growing in the likes of Steve Mandanda, Giannelli Imbula and Mathieu Valbuena, it's N'Koulou who is attracting interest, and with Marseille needing the money, he may well be sacrificed this summer.
Bundesliga side Borussia Dortmund and former club Monaco have been credited with an interest in N'Koulou, whilst Rafa Benitez's Napoli had a €12m bid rejected for him in the January transfer window. French press speculate that all three sides are still interested in a move, but Arsenal have also been watching his progress.
The Gunners' title challenge has fallen apart in recent weeks and they could now miss out on a top four place, with Everton now breathing down their necks for a Champions League place. Manager Arsene Wenger is under increasing pressure after nine years without a trophy, and he will need to make some signings in the summer to appease the fan base.
N'Koulou may not be the flashiest signing, but whilst he isn't the tallest at under six foot tall, N'Koulou has shown the ability to win with his athleticism, and with Thomas Vermaelen possibly leaving the Emirates Stadium this summer, Wenger will need to bring in defensive cover - but with N'Koulou set to feature for Cameroon at the World Cup this summer, he may need to make his move quickly as interest grows.