Chelsea have officially announced the departure of chief executive Ron Gourlay after a decade at Stamford Bridge.
Gourlay joined the Blues in 2004, just one year after Roman Abramovic took charge, and in 2009 replaced Peter Kenyon as Blues chief executive.
Having previously worked at Manchester United, Gourlay has been present in all of Chelsea's recent success, winning three Premier League titles and the Champions League in 2012, since Abramovic's arrival at the club.
Gourlay was also said to play an important role in the return of Jose Mourinho to West London, and he oversaw the summer trasnfer overhaul, which included the signings of both Diego Costa for £32m and Cesc Fabregas for £26m.
"Chelsea Football Club announces that Ron Gourlay, after 10 successful years at the club, including five as chief executive, is leaving Chelsea in order to pursue new business opportunities," Chelsea announce in the club official website.
"The club, and in particular the owner and directors, wish to thank Ron for his many years of service to Chelsea and support his desire to seek new challenges. Ron's efforts have helped the club to achieve its position as one of the leading football clubs in the world."
While Chelsea are yet to name a new chief executive, Chairman Bruce Buck and Director Marina Granovskaia will take on Gourlay's responsibilities.
"Pending additional appointments, Chairman Bruce Buck and Director Marina Granovskaia will assume additional executive responsibilities."
Meanwhile, Gourlay has explained his decision, claiming he wants to "move on to other challenges".
"It has been a privilege to have played a role in the club's considerable achievements both on and off the pitch over the last 10 years, but I feel the time is right to move on to other challenges,
I would like to thank Mr Abramovich, the directors, the manager and players and all the staff for their support during my time at the club, and wish them much continued success in the future."