Chelsea

The 76-year-old has been in the position since 2003, the same year that Russian billionaire Roman Abramovich took over the Premier League club.

Buck has since played a key role behind the scenes during the Blues' most successful era both on and off the pitch, helping the West Londoners become established as one of the biggest clubs in the world.

However, just three weeks on from Abramovich officially departing Stamford Bridge, the American has taken the decision to step down and make the transition to a senior advisor.

Speaking on the club's official website, Buck said: "I am proud to have helped Chelsea realize great success on the pitch and make a positive impact in the community.

"Now is the right time to step down and let new ownership build on the strong foundations we have in place. The owners have a compelling vision for Chelsea's future, and I look forward to helping them achieve it in this new role alongside our incredible staff, players, coaches and supporters."

A consortium led by Todd Boehly have now taken over the reins at Chelsea, and Buck's compatriot - who is described as the club's co-controlling owner - has also commented on his exit.

Boehly said: "Bruce has led Chelsea Football Club to the highest levels of international and domestic football, while also developing one of the most active social responsibility projects in sport. We thank Bruce for his service and his commitment to the Club."

While Buck has been in a leading role behind the scenes, Chelsea have collected 18 trophies, including five Premier League titles and two Champions League trophies.

As it stands, no announcement has been made regarding a successor.