Lyn Jones has been at the helm with Ospreys since the club's inception in 2003 but today the coach announced he is to leave the Welsh outfit by mutual consent to take up a new challenge.
Under Jones the Welsh region enjoyed EDF Energy Cup success at Twickenham and reach the last eight of the European Cup this season. But the Ospreys board confirmed that a global search for a coach of "worldwide calibre" was now underway.
"Lyn has done an outstanding job in his time as Ospreys head coach and, without doubt, has been the most successful coach in Wales since the onset of regional rugby," said Roger Blyth, Ospreys managing director.
"He successfully led us through our challenging formative seasons, taking on probably one of the hardest jobs in UK rugby by successful combining the rugby playing cultures of Neath and Swansea into a new dynamic.
"He developed the squad into winners of the Celtic League in 2005 and 2007, and this season led the region into the European Cup quarter-finals as well as winning the EDF Energy Cup, while contributing 14 players to the Wales squad.
Jones enjoyed the challenges at Ospreys but is now look ahead for new challenges.
"The last 10 years have been a tremendous time for me personally and professionally, both at Neath RFC and subsequently, at the Ospreys," said Jones.
"We've come a very long way since the summer of 2003 when Neath and Swansea came together to form the Ospreys, and I take great satisfaction in our many achievements over the past five years.
"The region now stands as one of the leading sides in European rugby and that is something that I know everybody involved at the Ospreys is proud of.
"Having achieved the success, I feel its now time to get my teeth into a new challenge and look for fresh horizons. Equally, I believe with my job firmly done at the Ospreys it is the best time for a new hand to come in and move the Ospreys to its next level of development.
Andrew Hore, the region's Elite Performance Director, will be instrumental finding a replacement for Jones.
During the recruitment process assistant coach Sean Holley and forwards coach Jonathan Humphreys will continue under Andrew Hore's guidance.
"Our challenge is now to recruit a coach of worldwide calibre, capable of picking up the reigns from Lyn to drive the region forward and accelerate our development," added Blyth.