Ryan Sachs (left)

American-born Sachs was an unknown figure to many Sunderland fans, yet he has been involved with the club’s transfer negotiations over recent seasons.

After initially joining Sunderland as an assistant to then director of football Roberto De Fanti, Sachs was promoted to club secretary and continued to work alongside Lee Congerton.

Sachs had been involved in contract negotiations and transfer discussions when Congerton was director of football, but is understood to have held a lesser role over recent months.

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The abolition of Sunderland’s director of football / head coach system has seen manager Allardyce take a leading role over transfers, alongside head of recruitment Martin Glover.

Glover was reunited with Allardyce in January after leaving Leeds United, following previous spells with the Black Cats boss at West Ham and Blackburn.