Championship Millwall have announced that Kenny Jackett has resigned as manager of the club.
The 51-year-old had been in charge of the Lions since November 2007.
"After almost six seasons I personally feel the time is right for a new challenge, and also for a new manager to come into Millwall with fresh ideas," he said.
"I would like to thank the chairman, the board of directors, players, staff and supporters for their backing."
A statement on the Millwall website said the board of directors had accepted Jackett's resignation "with reluctance".
"I want to express my thanks to Kenny for his fantastic service and achievements over the past five and a half years," Millwall chairman John Berylson said.
"He has played a major role in creating a stable environment at Millwall which hadn't been the case prior to his arrival.
"Whilst respecting Kenny's decision, I wish I could have persuaded him to change his mind.
"He was my first acquisition as chairman of the club and has proved himself to be one of the best. I am losing a great manager but he will remain a good friend.
"I know everyone associated with Millwall will wish Kenny all the very best with his future endeavours.
"We are now determined to move the club forward and build on the foundations Kenny has provided towards even greater success."