John Terry says he will "forever be indebted" to Aston Villa boss Dean Smith after leaving his assistant head coach role to pursue management.
The former Chelsea and England defender joined Smith's coaching staff in October 2018 and helped Villa earn Premier League promotion in 2019.
Terry said working with Smith was "the best education I could ever have had".
"I have loved every minute of it and learnt so much from you," the 40-year-old wrote on Instagram.
"I'm proud of what we have achieved at the club you loved and supported growing up.
"Aston Villa will always have a special place in my heart."
On Monday, Terry outlined his plans to pursue a career in management after leaving his position at Villa Park.
He was linked with the vacant positions - both now filled - at Bournemouth and Celtic in February.
"It has always been my ambition to move into football management and, providing the right opportunity presents itself, I feel ready to take up such a challenge," he said.
Terry said it was "an extremely difficult decision to move on" and added: "I want to be as respectful to the manager and everyone at Aston Villa as I can. Having given my future serious consideration over the summer, I don't feel it is fair to move into a new season without being certain of seeing that through.
"My immediate plan is to spend some quality time with my family and, thereafter, hopefully take up some invitations to visit clubs and managers around Europe to develop my aim and objective of becoming a manager."
Following promotion to the Premier League, Villa reached the Carabao Cup final in 2019-20 and, after surviving on the final day of their first season back in the top flight, finished 11th last term.
Smith said: "I'm disappointed to lose John as part of my coaching staff but fully understand and respect his decision.
"John has played a huge role in the success the club has enjoyed over the past few years and has been very supportive of myself throughout that period.
"I have no doubts he will go on to be a first-class manager in his own right and wish him well for the future."