This weekend's Valencia season finale will mark the final grand prix appearance for double MotoGP champion Casey Stoner.
The Australian made the shock announcement that he would retire at the end of this season on the eve of the Le Mans round, in May.
“This sport has changed a lot and it has changed to the point where I am not enjoying it. I don't have the passion for it and so at this time it's better if I retire now,” said Stoner, who recently turned 27 years old.
Stoner added that he was announcing his decision early to allow Honda time to find a replacement and to prove that his decision was not influenced by the championship outcome.
Stoner was leading the standings by one-point from Jorge Lorenzo
at the time of his announcement, but had slipped to third in the points when he was injured at Indianapolis, forcing him to miss three races.
That also ended his hopes of a third title, but Stoner has improved in each round since returning from surgery, culminating in a dream final home appearance at Phillip Island, where he dominated every track session and won for the sixth time in a row.
"Valencia should be a little better for me again, not as good as Phillip Island, but I've always had great success there, many pole positions and race wins,” said Stoner.
"I hope we can be competitive there and with the track going left it should suit our bike and me a little better at this point.
"It's not going to be easy, but it would be nice to get another good result in my final race in MotoGP."
A winner of two 125cc and five 250c races, Stoner claimed Ducati's only MotoGP title at his first attempt in 2007 - then won 13 more races on a bike that all others have struggled to even take podiums with, before switching to Honda and instantly claiming a second world crown in 2011.
The 27-year-old's 38 MotoGP wins since his 2006 premier-class debut is more than any other rider has achieved during the same period.