Monster Yamaha’s Jonas Folger has ruled himself out of the entire 2018 MotoGP season so he can fully recover from the illness that wrecked the latter half of last year.

Folger’s problems began before the Motegi MotoGP round where he struggled to even leave his room such was the exhaustion he was suffering, and he didn’t ride again for the rest of the year.

Doctors finally diagnosed him with Gilbert’s syndrome - a genetic disorder that prevents the liver from correctly processing bilirubin.

“I’m incredibly sad to be saying this, but I will not be racing MotoGP in 2018. I wasn’t able to make the improvements I was hoping for, and at this stage I don’t feel able to ride a MotoGP machine at 100 percent,” said the German.

“I’d like to thank everyone involved, but especially the Monster Yamaha Tech3 team, Yamaha Factory Japan, Monster Energy, HJC, IXON, Forma Boots and Rudy Project. I hope to be back one day and want to thank you all for your ongoing support.”

Team boss Herve Poncharal now faces the tough task of finding a replacement for this year.

“Last night (Tuesday) I received a call from Bob Moore, Jonas Folger’s personal manager. I couldn’t believe what Bob was telling me on the phone, that Jonas Folger has decided not to race the 2018 MotoGP season, because he doesn’t feel 100 per cent mentally and physically recovered," said the Frenchman.

"It is still very difficult for me to believe, that he’s not going to race with us in 2018, especially because he has been somebody I had lot of faith in and I was sure we would reach top level together this year. I completely respect his decision, although it’s hard to swallow.

"Yet, I will try to find a solution for a replacement rider, which is a very difficult mission, as all of the fast riders are already contracted. But as always in racing we need to be proactive, inventive and hopefully we can make someone very happy. We will keep all of you informed about the evolution of the situation.”