The Bursaspor defensive midfielder, who can also play at centre-back, arrived at the club's training ground on Tuesday to discuss a move to Wearside from the Turkish Super Lig club.
Black Cats boss Martin O'Neill is hoping to secure the 22-year-old's signature and get him registered in time for this Saturday's Premier League match against West Ham at the Stadium of Light.
N'Diaye signed for Bursaspor from Ligue 1 side Nancy last year for a fee reported to be £2.5 million and could sign for Sunderland for a fee believed to be around £3.8 million.
The Black Cats would still need to secure international clearance for N'Diaye if he agrees personal terms and passes his medical in time for him to participate in this weekend's game.
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