Graeme McDowell has announced that he is to leave Horizon Sports Management and will manage his own commercial interests from the end of this year.
McDowell, 35, linked up with Horizon in 2007 and since then he has won the 2010 US Open, played in the Ryder Cup three times and climbed the world rankings.
Rory McIlroy left Horizon last year and has begun a legal action in Ireland against the Dublin-based company.
This is understood to involve a multi-million euro dispute over fees.
The details of the case have not been outlined but it is believed the current world number one viewed the fees charged by Horizon, said to be £6.4m over an 18-month period, as excessive.
|"I am at a stage in my life where it feels right to move on to the next phase of my career - both in golf and business."|
The development was thought to have put the previously close relationship between Northern Ireland's top two golfers under strain.
"When I joined Horizon in November 2007, I was ranked outside the top 100 players in the world. I was seeking a new and energetic management team to help me achieve my career ambitions on and off the course," outlined McDowell.
"These ambitions have not only been achieved, but have surpassed my highest expectations," added the Portrush man.
"During my time with Horizon I have become a major champion, played in three successive Ryder Cups and won multiple tournaments around the world.
"I am at a stage in my life where it feels right to move on to the next phase of my career - both in golf and business."