Graham Potter says he felt he had to “grasp a new opportunity” as he explained in an open letter to fans why he left Brighton to join Chelsea.
47-year-old Potter became Chelsea manager on Thursday after three years at Brighton.
The former Ostersunds FK of Sweden and Swansea City manager Potter led Brighton to ninth place in last season’s Premier League, the highest finish in their history.
He has guided them to fourth in the table this season after they won four and drew one of their first six Premier League games.
The Englishman wrote: “I hope that you will understand that at this stage of my career, I felt I had to grasp a new opportunity.”
“For some, I recognise that the change that comes so suddenly in football can be hard to accept,” he added.
“I may not be able to persuade you all to forgive my departure – but I would at least like to take the chance to say thank you.”
He is yet to take charge of the Blues in any official game but many believe he will hit the ground running at Stamford Bridge.