Arsenal's chief transfer negotiator Dick Law will step down at the end of the month, leaving Arsene Wenger without one of his key allies at the club.
The Gunners have confirmed that Law will leave the job and is set to return home to the United States for family reasons.
Law has been in charge of Arsenal's transfers for eight years and previously worked as a scout in South America. He played a key part in signing Mesut Ozil in 2013 but questions over his role have been increasingly raised after a series of transfer windows in which Arsenal struggled to land top targets.
This past window saw the Gunners beat several clubs to the signings of Sead Kolasinac and Alexandre Lacazette, but they struggled to offload unwanted players and failed in a £92-million bid for Monaco's Thomas Lemar on deadline day. That also killed a deal to send Alexis Sanchez to Manchester City, and Arsenal face a potentially turbulent summer next year when Sanchez, Mesut Ozil and Jack Wilshere are among players whose contracts will run out.
It is unclear whether Law will be replaced, with Arsenal having hired contract expert Huss Fahmy from cycling's Team Sky in the summer. Chief executive Ivan Gazidis had also been pondering the idea of hiring a director of football last year, but those plans were apparently shelved when rejected by Wenger, who was given a new two-year deal in May.