John Mensah has agreed personal terms with Sunderland but his move is subject to the Home Office's approval.
Black Cats boss Steve Bruce has confirmed that the Ghana international could be the club's final signing of the summer.
Mensah is expected join Sunderland on a season-long loan deal from Lyon with the French side having also agreed to the transfer.
"It is still ongoing," Bruce said of the Mensah deal.
"He is a Ghanaian international, it's all Home Office, papers and passports all this sort of stuff.
"In principle the two clubs have agreed, the boy wants to come to us and to England so in that respect we are over that hurdle, but we have to make sure we dot the i's and cross the t's and we expect him obviously before the window closes that he can be part of us."