Chelsea have announced Michael Emenalo has stepped down from his position as technical director.
Emenalo first joined the club in 2007 and has played a key role behind the scenes in the development of Chelsea's first team and academy.
In the 10 years Emenalo has been involved with the club, Chelsea have won three Premier League titles, three FA Cups, the EFL Cup, Europa League and Champions League, playing a major part in the assembling of those successful squads.
He became technical director in 2011 and led the Blues' scouting and transfer activities.
Emenalo said in a statement: "This has been a very difficult decision to make, but one I believe is right for both myself and my family, and the club.
"I have had the privilege to work alongside some of the most talented people in the world of sport over the past 10 years, and I will depart incredibly proud of the achievements we have made.
"I wish Chelsea every success and look forward to following the club's future triumphs from afar."
Emenalo's work has also had a huge impact on Chelsea's success at youth level, with the club winning the FA Youth Cup six times in eight years and emerging triumphant in the UEFA Youth League on two separate occasions.
There have previously been reports of Emenalo and head coach Antonio Conte having a frosty relationship, but the Italian says he is sad to see him go.
"I am very sorry to see Michael leave Chelsea, and I would like to thank him for all his help and support since I arrived at this club," Conte commented.
"I have enjoyed working with him very much, we celebrated a Premier League title together in May, and I wish him the very best for the future."
Chelsea will review their management structure in the wake of Emenalo's departure but revealed he will be involved in that process.