Ospreys coaching director Scott Johnson is to quit his post at the end of this season.
Announcing former Wales coach Johnson's decision, the Ospreys said he will "pursue other opportunities".
Apart from his involvement with Wales and the Ospreys - he took up his role with the Swansea-based region in April 2009 - Johnson is a former Australia assistant coach and United States head coach.
The Ospreys were Heineken Cup quarter-finalists and Magners League champions during Johnson's first full season in charge.
Although they are again well placed in this season's domestic league, a Heineken Cup pool stage exit beckons next month following home and away defeats against English champions Saracens.
Johnson said: "Having initially committed myself to the Ospreys for three years, I've taken the time to consider my future plans and have advised the directors that while I intend to see out the remainder of my contract I will not be looking to renew at the end of the season.
"When I joined the region I had a remit to help set up systems that would enable us to bring through home grown talent, coaches and players, a challenge I've thoroughly enjoyed getting my teeth into over the last three years.
"I feel that now is the right time for me to move on to other challenges, but I remain 100 per cent committed to the Ospreys between now and the end of the season."
Johnson informed Ospreys directors of his decision ahead of yesterday's Welsh derby defeat against the Scarlets.
Ospreys chief operations officer Andrew Hore described Johnson's departure as "a huge disappointment".
Hore said: "It is a huge disappointment for us to be losing Scott at the end of the season, but we understand that he feels it is the right time for him to move on to other challenges having served the three years he committed himself to us for originally.
"In 2008, we started a process which would see the Ospreys become a world-leading player and coach development organisation, with Scott joining us a year later as a part of this to assist in producing such a development programme.
"Although this is now the end of the second phase, this process continues.
"As a region we have enjoyed success during his time with us, but his biggest influence has been off the field, where he has played a major part in putting in place these new player and coach development structures while also having to deal with reducing the wage bill for the long-term good of the business.
"His work will help to ensure the long-term sustainability of the Ospreys.
"He will be sadly missed by everybody at the Ospreys when he moves on, but by informing us of his intentions at this early stage, it allows us to use this time to consider our next course of action and the options available to us as we plan for the future."
The Ospreys saw three of their Wales internationals - Mike Phillips, James Hook and Lee Byrne - move to French club rugby earlier this year, but under Johnson's guidance, promising young players have continued to be discovered and developed.
Ospreys managing director Roger Blyth added: "Scott is an innovative thinker who has worked tirelessly for the cause since joining the Ospreys.
"While he has brought silverware to the Liberty Stadium - and we hope that will be the case once again this season - the real legacy he will leave is the systems and structures he has helped to develop that will allow us to continue leading the way in Wales.
"The work he has put in over the last three years will ensure that the Ospreys continue to be known as a centre of excellence in development terms.
"In doing so, it will allow us to continue to compete at the top level, despite the ever-increasing financial pressures we face both locally and from outside of Wales. We wish him the very best of luck for the future."