Between them Rossi and 60-year-old Aussie Burgess have won seven world titles (three with Honda, including the last 500cc crown, and four with Yamaha), but the past few years, including the disastrous Ducati experiment, have left the Italian rider frustrated over an apparent lack of speed and inability to challenge for race wins on a regular basis.
"It's not true that I'm unhappy with Jeremy's work, but it is true that next year he won't be my Chief Mechanic," Rossi said at Valencia's Thursday press conference. "It was a very difficult decision for me because I have a great history with Jeremy. He is not just my Chief Mechanic. He is like part of my family. My father in racing.
"But I've decided for next year I need to change something to try to find new motivation and to have a boost to improve my level, my speed. So this will be my last race together with Jeremy.
"We spoke today, face to face. Next year will be crucial and I need new motivation. In the last few races I've felt I wanted to work in a different way. It was a difficult choice to make. Yamaha had asked me some time ago, but I decided recently.
"In my head there is the idea of trying something new now. I've always done that in my career. Next year I have to earn a renewal with Yamaha, so I'll have to be competitive. I still do not know who will be the new chief mechanic."
With Burgess as his crew chief, Rossi was 500cc/MotoGP World Champion in 2001, 2002, 2003, 2004, 2005, 2008 and 2009.
In addition to his success with Rossi, Burgess also helped deliver championships for Mick Doohan and Wayne Gardner, and had been a Honda employee for more than two decades before he defected - with Rossi - to yamaha in 2004.
Whether Burgess will remain with the Yamaha Factory Racing team in another role, possibly with Lorenzo, or pursue other opportunities within the MotoGP paddock was not revealed at time of writing.