Peter Kenyon is to step down as Chief Executive of Chelsea from the end of next month, the English Premier League club said in a surprise announcement on Wednesday.
Kenyon will continue as a non-executive director and will represent the club in various committees of UEFA and the European Clubs' Association but his move from the senior executive position at the club will inevitably trigger speculation about possible differences with the club's owner Roman Abramovich.
In a statement announcing the switch, Kenyon confirmed that he would be looking for a new job, saying he felt he had "at least one major challenge left in me."
Kenyon, who controversially left the chief executive's job at Manchester United before joining Chelsea in February 2004, said: "I have been in football for 15 years and I can say with great certainty and pleasure the experience at Chelsea is one of the best I have had.
"When I joined Chelsea it was an incredible challenge and together with all the staff, the players, the board and Roman, I think we have really built a club, in a relatively short space of time, that can be in the forefront of European football for many years to come. That is a major achievement."
Kenyon added: "I intend to take a little time off before considering what I do next but I am certain I have at least one major challenge left in me."
Chelsea Chairman Bruce Buck implied Kenyon's decision to leave had been his own.
"When Peter first joined us we knew we were recruiting a top executive from business generally, not just football," Buck said.
"With that always came a certain inevitability he would eventually want to seek a new challenge and I am sure that is what he will do."
Kenyon's time at Stamford Bridge has been one of unprecedented success for Chelsea, with the club's emergence as a leading force in European football enabling the chief executive to negotiate record deals with sponsors including Samsung and adidas.
But the running of the club has not all been plain-sailing with Chelsea embroiled in a seris of 'tapping-up' scandals and the club's youth programme having conspicuously failed to provide a stream of talent to the first-team squad.