Valentino Rossi and Jerry Burgess to part company after 2013

Burgess has worked with Rossi throughout his MotoGP career, and was the technical mastermind behind the Italian's seven world championship crowns.

He followed Rossi to Ducati in 2010 - where the pair endured a disastrous two-year barren spell - and then did likewise when Rossi rejoined Yamaha for the start of this season.

Rossi has struggled to match team-mate Jorge Lorenzo this year however, which he says is the principal cause of his decision to split with Burgess.

"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.

"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."

Rossi said he had only made the decision recently, and after long deliberation.

"We spoke face to face," he said about his split with Burgess.

"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."

Rossi said he was yet to decide on Burgess's replacement.