The Frenchman has been in great form for Olympiakos this season.
Now reports are suggesting the fee that Sunderland might have to pay to bring in the 22-year-old talent. It was reported by the Hartlepool Mail recently that Olympiakos had slapped a £7 million fee on the player.
Sunderland scouts have reportedly watched him in action three times, including in the Champions League, this season.
But that fee would be a massive outlay on a defensive player.
However Sunderland do need a new left-back. Patrick van Aanholt has proved to be something of a liability in the position this term and Sunderland as a whole have conceded the most goals in the Premier League this campaign.